1

Biological Control - Natural Control and 2. Density dependent factors:

Balance of Nature a. Non reciprocal: E.g Some Foods,
Space territoriality.
Natural control is defined as the b. Reciprocal: Parasites, predators,
‘maintenance of the population dynamics pathogen, herbivorous, some food
equilibrium within particular upper and lower sources.
limits over a period of time by a complex
combination of all the environment factors In nature probable every insect
affecting upon the population’. The rebounding population is attacked to some degree by one or
of the population in returning to the more natural enemies, referred to
characteristic mean density after periods of entomophagous insects. Clausen (1940) stated
positive or negative excess is most important. that every phytophagous insect species is
Consequence of this result to a particular species attacked by such one or more parasitic or
continued to increase or decrease in number. predatory insects. Other predatory animals e.g.
This is called “Balance of Nature”. some birds, certain mammals, toads, frogs,
Lizards etc. can also act as natural control
The ‘Balance of nature’ is the result of agents.
natural regulative processes in the environment
of every living thing and it assures that a species The results of natural control are the
will neither decline in numbers to extinction not regulation of numbers, preventing the population
increase to infinite density. Regardless of from becoming too high or relaxing certain
whether a species is abundant or scarce, the suppressive influence when the population
average characteristic density of its population in becomes low. The occurrence of this situation the
a given habitat is constant. The importance of long term maintenance of the population at a
this ecological principle should be self evident characteristic level of abundance relative to other
for without it the living natural world would organisms in the community is the demonstration
cease to exist. of the “Balance of Nature”.

It is customary in biological control work The natural control is governed through

to describe the species of animals and plants influences of mortality factors and reproductive
which live at the expense of other animals and factors includes climatic factors such as
plants as natural enemies of the latter. Any given excessive heat, or cold or disappearance or
species in a community with few exceptions is deterioration of food resources, the action of
attacked and fed on by one or more such natural competing species and natural enemies. The
enemies, and indication of the tremendous environmental factors which act as mortality
potential for biological control. agents at intensities unaffected by the size of the
population e.g. weather this limiting factor is
The natural control generally limits the called a ‘Density Independent mortality
number of insects. Such checks to numerical factor’. Whereas those limiting factor whose
growth include limited resources (Food, Space, intensities of action vary with the abundance of
and Shelter) periodically occurring inclement the species in question e.g. predator which
(severe) weather or other hazards (Heat, Cold, consumes proportionally more prey when they
Wind, Rain, and Draught), competition from later are more abundant then when they are
themselves or from other kind of animals and scares is called ‘Density Independent mortality
natural enemies (Predator, parasites and factor’. Natural enemies have the capability of
pathogens) acting as density dependent mortality factor
though they may not act this way depending their
The major component of natural control of own environmental limitations. All natural
population numbers: enemies used in contributing to successful
biological control programmes act in this way.
Natural Control: 1. Density independent factors, Density depended factors may be classified
2. Density dependent factors according to whether they vary in number (or
magnitude) as the host numbers change
1. Density independent factors: (reciprocal action) or whether their numbers (or
a. Physical: E.g Temperature, Humidity, magnitude) remain fixed (non reciprocal action).
Air movement, Exposure. The parasitoids and predators are reciprocal in
b. Biological: E.g Host Suitability, Food action, since they commonly increase in numbers
Quality. when their host or prey become numerous as
decrease as the hosts or prey become suppressed.
 2

Thus the enemies control their hosts and the host number of native pest species. The agricultural
controls the enemies. Space is an example of a practices of the growers may often interfere with
non reciprocal factor since it does not mold the efficiency of natural enemies on exerting
(wax) or wane (decrease in area) as the user their share of natural control.
population rises or fall “space” can control the
numbers of the users, but the users do not alter Biological Control of Such Native Pest can
the amount of space present e.g. some then Assume Several Routes:
herbivorous insects can be limited by the amount
of “food” (host plant) available to them but often 1) The introduction of natural enemies of
do not influence the numbers of plants present the foreign origin which are associated with
for insect populations to remain in relative related pest species.
numerical balance within their normal
communities for substantial periods of time, it 2) The modification of agricultural and
appears to us necessary that there be one or more other practices with the intention of enhancing
density dependent mortality agents involved in native natural enemy action.
the natural control of such populations. Such
mortality agent being responsive to increase in 3) The employment of other pest control
the density of the population serve as regulators techniques, chemical control in particular, to
to check this increase as the population density bring about the integrated control of such pests.
declines the regulative action of these agents’
moderates allowing the population to rise again. Dynamics of Natural Population as a Basis for
Biological Control
When an insect population is maintained
at a characteristic level of abundance by the Some species of insects consistently
effects of natural control agents (including all occur in large number, an important
mortality agents, both density dependent and characteristics of insect population phenomenon,
density independent in action) usually there is a while others comparatively rare, e.g. Butterflies
substantial contribution from natural enemies to and Bollworms most abundant, Army population
the total mortality occurring in any generation. densities are maintained year after year, The
There are about 10,000 to 30,000 insects’ species absolute number of one or all of the species may
out of 1 million or more species of to be vary from time to time. The particular observed
recognized as economically important. When population densities are governed by the effect of
insect species invade new geographic regions some intrinsic (biotic) or extrinsic (abiotic)
either commercial activities of man or factors.
accidentally they may increase to extra ordinarily
high numbers mainly because they have escaped 1) The Ground Rules:
the controlling influences of their customary
natural enemies. Overall generation mortality is The study of the dynamics of natural
greatly diminished while reproductive capacity population has a long history. Thomas Malthus
of the space is remain high. The population of (1798) was the first to inquire into the means by
such high invades increases in numbers at an which population levels are maintained. He put
exponential rate, causing population outbreak. theory of human population dynamics as
When such an invading insect is injurious, pest “Population when unchecked increases in a
outbreaks occurs and the control efforts must be geometrical ratio”. Human population is
needed. These efforts directs to search for and regulated by flood, famine etc.
colonization of any adopted natural enemies that Charles Darwin (1859) put forward the theory
remain behind in the native home of the invading the struggle for existence, ‘stronger will survive’.
species. Virtually all successful classical He was the first biologist to deal with the relative
biological control programs to date have resulted importance of competition, predation and
from the re-association of invading pests of climatic factors in this regard. As early as 1700,
foreign origin with their adopted natural enemies Linnaeus considered the importance of certain
(De Bach, 1964). However, not all insects’ factors in the gross mortality of pests. Kollar
species are of foreign origin, some may include Fitch and Walsh during 1800 have notably
native also e.g. Cotton bollworm. emphasized particular mortality factors. Howard
The biological control of native pest species is and Fiske (1911) reported the various factors in
more complicated than foreign species because it population regulation of gypsy moths.
is presumed that the native species have already
associated with their natural enemies. There are
some other factors that favors unduly increase in
 3

2) Natural Control as the Ecological Basis for

Biological Control:
2. Substantial Biological Control:
Insect population density never remains
static but it is always fluid and changing. The If Biological control can be substantially
individuals which make up the population are successful economically for a period of time, the
dying of starvation, predation, exposure or partial so far becomes a subsequent period.
accidents and new individuals come into the
population immigration also take place 3. Complete Biological Control:
throughout the year. Thus, it seems that
population can be both stable and changing in Outstanding economic feature of
numbers at the same time. The population successful biological control is that once
density of an organism may be constantly achieved, it is essentially permanent. Also, it
changing, the value tends to oscillate about a does agree with man’s purposeful activity. For
mean which is comparatively stable, but may example, Rodolia cardinalis on cottony cushion
change under certain control. scale in citrus Epiricania melanoleuca on pyrilla
in sugarcane.
Definition of Biological Control
Method/Techniques in Biological Control
Biological control, when considered from
the ecological view point as a phase of natural Biological control practices involve three major
control, can be defined as “The action of techniques,
parasites, predators or pathogens in maintaining
another organism’s population density at a lower 1. Introduction
average than would occur in their absence”. 2. Conservation
(Paul DeBach, 1964). 3. Augmentation

This definition is more demographic and 1) Introduction:

ecological in context, but it does not explain the
mechanism of control or regulation. It is a factual It is advisable to introduce an exotic
type of definition in that Biological control can species of a natural enemy either when there is
be measured experimentally but man’s activity or an unoccupied niche and is required to be
manipulation of natural enemies not implicit / displaced by a more efficient exotic species. The
exhibited. Hence, in more precise way as an former is a common situation in newly
applied control, Biological control can be introduced pest in a country. Foreign
defined as “The destruction or suppression of explorations for parasites and predators have
undesirable insects, other animals or plants by been made primarily to introduce parasites from
the introduction, encouragement or artificial the place of origin of the pest and sometimes to
increase of their natural enemies”. introduce exotic natural enemies of the
indigenous pest species.
Types of Biological Control
Recently, many international organization
Biological control involves regulation of have been established to facilitate the movement
organism’s population density at any given level of beneficial species from one country to another
by natural enemies. If Biological control factors and the largest of the organization is the
are responsible for population regulation of an ‘International Institute of Biological Control’
organism below density which would be adverse which has laboratories in Switzerland, Trinidad,
to man’s interest, then it is a case of successful Malaysia and Pakistan. About 40% of the
biological control in economic sense. introduced natural enemies have established in
the introduced countries and provided partial to
1. Partial Biological Control: complete control of important insect pests at the
global level.
If control is achieved at somewhat higher
average population densities than it is 2) Conservation:
economically satisfactory, this is sometimes
alluded to as partial Biological control. Conservation means the avoidance of
measures that destroy natural enemies and the
use of measure that increase their longevity and
reproduction of the attractiveness of an area to
 4

natural enemies. If the natural enemies are periodic releases may be either Inoculative of
properly conserved the need for other control Inundative.
measures is greatly reduced.
i) Inoculative Release:
i) Preservation of Inactive Stages:
Inoculative release may be made as
This is most critical when there is small infrequently as once a year to re-establish a
reservoir of natural enemies outside the cropped species of natural which is periodically killed out
area e.g. Pupae of Epipyrops are found in large in an area by unfavorable conditions part of a
numbers on the trashes of sugarcane leaves at the year.
time of harvesting. These are left around
harvested fields to augment the supply of natural ii) Inundative Release:
enemies in the pre-monsoon season against
pyrilla. Inundative release involves mass culture
and release of natural enemies to suppress the
ii) Avoidance of Harmful Cultural Practices: pest population directly. These are most
economical against pests that have only one or
Cultural practices like burning can be few discrete generations every year e.g. massive
harmful to natural enemies e.g. burning of release of Trichogramma spp.
sugarcane trash destroy the resting stages of
Epipyrops. Such practices can be modified to Scope of Biological Control
avoid harmful effects.
In the years ahead, workers in Biological
iii) Maintenance of Diversity: control of insects, mites and seed pest
suppression must continue to deepen and
The concept on more diversity is stability broaden their efforts, as this field has received
holds true because diverse system may provide great enthusiastic acclaim during past century.
alternate hosts as source of food, ever wintering These research workers showed successful
sites, refuges etc. e.g. mixed cropping, practical results in more than 60 countries of the
intercropping etc. world. The partially exploited field has several
dimension of future scope.
iv) Natural Food, Artificial Food Supplements
and Shelters: 1. Promoting Basic Research:

Many parasitoids and predators require There is lot of scope to intensify the
food frequently not available in monoculture. studies which can improve and synergize the
The availability of predatory mites was related to biological control. Basic research areas in the
the availability of pollen. Artificial honey dew field of biology, ecology, biosystematics,
and pollen in the form of food sprays induced behavior, biochemistry, population dynamics etc.
early ovipositor of Chrysopera spp. have great contributing value to biological
suppression which needs to be studied.
v)Protection from Pesticides:
2. Scope to Exploit the Bioagent on Crop Pest:
All pesticides have adverse effects on
natural enemies. The solution lies in the use of About 98 % of the insects pests are
relatively resistant strains of natural enemies and regulated naturally through natural enemies.
selective use of pesticides. However, it is reported that only 5% of the world
insect pest species have ever been the subject of
3) Augmentation: entomophage introduction (DeBack, 1974). It is
estimated that 70% of parasitic hymenoptera are
Augmentation includes all activities still undescribed species.
designed to increase numbers or effect of
existing natural enemies. These objectives may 3. Help to Reduce Pollution Hazards:
be achieved by releasing additional numbers of a
natural enemy into a system or modifying the Utilization of bioagent can help in
environment in such a way as to promote greater establishment of population regulation process of
number or effectiveness. These releases differ serious pests by reducing the load of toxic
from introduction of imported natural enemies in insecticides and their side effects.
that these have to be repeated periodically. The
 5

4. Necessity to Intensify of New Horizons of Constrains in the adoption of Biocontrol

Biological Control: (Limitations)

Importation and use of parasitoids and Biocontrol is slow process and takes little
predators is popular concept of biological more time to achieve control of crop pests. The
control, which gave good success in several possible constrains are:
cases. Similarly new trends such as use of
biotypes, strains, hybrids of parasites, use of A) At farmer’s Level:
novel biopesticides like entomogenous fungi,
viruses are to be search properly and its 1. Non availability of biotic agents for field
harmonious use in pest suppression needs to be application timely.
exploited. 2. Illiteracy among farmer as they have no access
to new technologies to read.
5. Adoption of Biological Control Methods in 3. Small holdings may cause migration of
Agro Industries: bioagent.
4. Inclination towards use of chemical pesticides.
Although use of bioagent has many 5. Non availability of popular literature.
benefits but there is need to adjust with other 6. Population lacking.
methods like chemical control of pest. The
pesticides should be less toxic to natural enemies B) At Government Level:
and needs to be identified and employed in pest
control suppression. For example, Endosulfan
safe to many predators and social insects. 1 Relatively less attention to Biocontrol projects
Biological control helps in maintaining ‘Balance than chemical industries.
of Nature’ as it is the phase of natural control. 2. Importation of biotic agents.
3. Mass production of biotic agents limited
techniques for indigenous and exotic use.
4. Field Utilization of biotic agents.
Practical significance of Biocontrol 5. Integration of bioagent with pesticides.
(Advantages) 6. Laboratory evaluation of biotic agents and
their field efficiency.
1. It is exercised in a wide area. 7. Transfer of technology requires more attention.

2. The application of biotic agent is easy and Historical Developments in Biological Control
possible in inaccessible areas like dense
forest. The purposeful control of insect pests and
weeds by biotic agents is a comparatively
3. It is safe for humans and animal health. modern development having become effective
techniques in pest control only since 1890.
4. The biotic agents survive in nature till the pest However, there are antecedent historical events
is prevalent. which trace the evolution of some of the
fundamental concepts in the development of
5. It is a cheaper method if successfully deployed Biological control.
and persuaded.
The overall population of Rachel
6. It is a self perpetuating in nature. Carlson’s “Silent Spring” in 1962 had gained
increasing acceptance in very recent years
7. It has no risk of environment pollution. through various practices of biological control
method. Historically, the growth of discipline
8. It does not require special equipment to apply was much slow and painful.
and can be mass multiplied at farmer’s
level. The historical events could be identified with
following developmental periods:
9. It may provide/generate employment revenues
to rural people. A) Early History to 1888 (Ancient period)

10. No problem of pest resistance and B) Middle History to 1940

resurgence.
C) Middle History to 1962
 6

D) Recent Advances 1962 Onwards pupal parasitoid of hesion fly Asalitch (1845)
proposed importation of parasitoids from
Historical Developments in Biological Control England to America to control wheat midge.
- Early history to 1888 (Ancient period) Agostina Bassi (1835), a pioneer insect
pathologist first demonstrated the fungal nature
The idea that the insects could be use of mustarding disease of the silk worm. Kirby
intentionally to suppress the population of other and Spence (1867) recommended and used lady
insect is an ancient one. Charles Darwin bird beetle for aphid control. They were also
recognized appearance of first insect primitive aware of usefulness of mantids, coccinlids,
humans probably utilized insects as a part of dragonflies, spiders etc.
their own field diet. It assumed that man himself
recognized perdition at an early date by man Historical Developments in Biological Control
himself. The discovery of agriculture and - Middle History to 1940
development during Neolithic time (about 1000
BC) put human kind into very direct competition The knowledge about parasitoids,
with insect for food. Just as early as man predators and diseases were accumulating and
observed birds eating insects, snake eating the struggle for existence was taking place an
rodent, mice and rats eradicated by house cat by early Ecologist George Russel Wallace and
Egyptian. Charles Darwin put forth general idea called
‘Balance of Nature’.
“Historia Animalium” described the
ravages the wax moth to honey comb. Later on John Curtis in his book on ‘Farm Insect’
Pliny (23-79 AD), a Roman author recognized (1860) includes ecology of various agricultural
several disease conditions in bees. Silkworm also pests and emphasized functions of parasitoids
suffers from various diseases and recognized as and predators in crop protection. Riley (1873)
early as 1000 AD. The true biological arranged first international shipment of natural
suppression of insect pest in modern sense was enemies in the transfer of predatory mite
practiced by Chinese citrus growers by Tyroglyphus phyllaxerae to France from North
introducing predaceous ants in to orchards to America for possible control of grapevine
control citrus peat. In the old Chinese book phylloxera. Riley (1883) directed import of
‘Wonder from Southern China’ (900 AD) refers internal parasite of cabbage butterfly from
that large yellow ants with long legs used to England to America and A. glomeratus
protect oranges from worms and ant’s nest was eventually, become successful and well
available for sale in village markets ‘Anton’ until distributed in Eastern and mid western state as
1939. larval parasitoid. This successful importation of
A. glomeratus by Riley was the first international
Ulysses Aldrovandis in his book “De transfer of parasitoid for biological control.
Animalibus Insects” (1802) summarized all
published literature on insects and included first The Italian Microbiologist Agastina Bassi
published literature on insect parasitism. An is the first worker to suggest use of microbes for
attack of Gregarian parasitoid, Apanteles insect pest suppression in 1836. Lewis pasture
glomeratus of the cabbage butterfly was known. from France was more confident for his
Francisco Redi (1860) described phenomenon of suggestion of use of protozoa causing pebrine
parasitism of aphid by an ichneumonids. disease in bees. Russian Zoologist Metchnikiff
Vallisnleri (1730) first noted unique association recorded large fluctuation in pest population of
between parasitic wasps, A.glomerctus of wheat cock chafer beetle and one of the causes
cabbage butterfly. Rene Reanmur (1734) was green muscardine fungus, Meterrhizium
advanced the idea of biological insect anisopliae.
suppression and suggested introducing the eggs
of aphidivorous flies (lace wing) into green The successful introduction of coccinellid
houses. A lady bird beetle, green lace using and beetle Radalia cardinalis from Australia to
wasp were also recommended for suppression of California in 1888, was the first spectacular
aphids. The first International Movement of success controlling cottony cushion scale (Icerya
predator was accompanied in 1762. The Indian puchasi) a serious pest of citrus and become a
‘Mynali’ bird was introduced from India to first classical example of biological insect pest
Maurtius with a purpose of red locust control in suppression and it was later acclaimed as miracle
sugarcane. Mitchill (1823) discussed various Cryptolaemns montrouzieri. Mulsent, a mealy
parasitic animals including hymenoptera form bug predator approached usefulness as like that
insects. Herrick (1840) discussed an egg and of R. cardinalis (vedalia beetle). However Smith
 7

H. S. (1912) put quarantine measures to stop Control) comparing of 22 members from 16

importation of beneficial organisms into Countries. The group was designed to promote
California. In 1919, he was first to propose the and co-ordinate the national efforts in biological
term ‘Biological Control’ and wrote pest suppression by international cooperation
voluminously in 1935-1939 on theoretical within its jurisdiction. This organization began a
aspects of biological control. publication of a Journal “Entomophaga”.

In Europe, Metchnikoff tried Beauveria In Canada, F. T. Bird carried out studies

sp against nunmoth caterpillar, Gypsy moth and and accidentally introduced polyhedral viral
Melolontha beetles. In mid western U. S. the species and it was the beginning of a period of
fungus, B. basiana was used for control Chinch applied Insect Pathology By 1950, a well
bug, Blesses leucopterus. In 1920, Albert koebele equipped insect pathology laboratory was
used successful biological programs against leaf established in Sault SteMarie concerning with
hoppers by introduction of egg parasitoids from disease of forest pest and another group in
Australia and a predacious mired bug. Dominion Research Laboratory at Belleville was
concern with agricultural pest.
First modest biological control laboratory
in Canada was established in the University of During 1940-50 work on biological
New Brunswick and by 1960 when importation control was mostly restricted in USDA,
was stopped. Three important parasitoids had California and Hawaii. Largest effort was made
been established as a footing stone for future for biological control of oriental fruit fly, Dacus
development. Parker and Thompson set dorsalisand obtained substantial control. In 1955,
laboratory in France and during 1927-40 Dominion laboratory Belleville had become one
imported several parasitoids for biological of the largest centers for research on application
control of European corn borer, Ostrilia nubilalis. of principles of genetics for mass production of
Baird (1923-56) carried out corn borer parasitoids in the world with the name
suppression program in Canada for alfa weevil. Entomological Research Institute of Biological
Japanese beetle and European Ear wig with the Control. The CIBC has headquartered at
help of USDA, Bureau of Entomology. In 1929, Belleville during 1940-46 at Ottawa during
Canadian Entomologist established Dominion 1946-61. From 1961 onwards the headquarter of
parasite Laboratory at Belleville and then new CIBC was moved to Trinidad, West Indies and is
era of biological control was dawned by 1933. In continued until now. In 1959, a growing interest
1940, because of World War II, the Fernharn in Insect disease gave impetuous to the
laboratory (U. S.) was closed and Thompson publication of Journal of ‘Insect Pathology’ in
service later recognized as CIBC i.e. Common New York which has been changed to Journal of
wealth Institute of Biological Control. ‘Invertebrate Pathology’.

Historical Developments in Biological Control Historical Developments in Biological Control

- Middle History to 1962 - Recent Advances 1962 Onwards

In 1874, a German Chemist Othman Impact of Book Silent Spring (1962) on

Zeidler synthesized DDT and later in 1939 Paul the practice of pest management resulted in wide
Muller in Swiss discovered its remarkable discussion concerning about developing
insecticide properties. Thus during 1940-1960 problems of synthetic insecticides. This
insect control was totally dependent upon use of discussion has led to search for alternative
chemicals. In 1950 use of BT resume interest in methods of pest control. Thus again
Europe and America and significance of Bt strengthening of research on parasitoids,
resulted its commercial production in 1960. predators and pathogens was initiated for
There, was increasing emphasis on use of ecofriendly approach in pest suppression.
microbes and other methods of pest control like
chemical, physical, and cultural for greater Two multinational co-operative groups
effectiveness. i.e. CIBC and IOBC organized to promote cause
of biological control become stronger than ever
In 1952, another significant development more than half dozen field stations were
was the establishment of International maintained around the world to provide
Commission of Biological Control (ICBC) under collection and rearing services of natural
the auspices of International Union of biological enemies. In India, (CIBC) center was located at
Scientists. ICBC was later recognized as IOBC
(International Organization for Biological 1. There are 5 regional stations:
 8

2. West Peleactic regional action. Antibiosis:

3. Western Hemisphere regional section. According to Painter (1951), it refers

preventative, injurious or destructive effects on
4. SPE Asian regional section. the insect life history which result from the
insect’s use of a resistant host variety or species
5. Tropical Africa regional sections. for food.

6. Pacific Regional section. Antifeedant:

IOBC remained the important channel for A natural synthetic chemical substance
the exchange of ideas and information regarding which acts either to inhibit the stimulation of
biological control on a worldwide basis. In 1962, gustatory receptors which normally recognize
the predaceous snail, Euglaelina roses F. was suitable food, or to stimulate receptors which
introduced from Bermuda and it was released in elicit a negative response to deterrent chemicals.
Orissa to control a new pest i.e. Giant African
snail, Achatina fulica F. So far 120 pests in 65 Arrhenotoky:
countries of the world have been controlled by
using biological control. A facultative type of parthogenetic
reproductive in which only male progeny are
In 1962, prickly pear, Opuntia dillenil produced.
was controlled by cochineal insect Doctylopis
tomentosus covering area of about one lakh acre. Augmentation:
Successful introduction of lepidopterous nymph
and adult parasitoid, Epiricania melanoleuca It is the process which involves to
against sugarcane pyrilla, predator C. improve the effectiveness of natural enemies by
monstrouceiri against mealy bugs. Zygogramma manipulating either mass production, periodic
bicolorata beetles feeding on parthenium weeds, colonization or by genetic improvement.
Apentelus sp. Beacon sp. the research was in
progress. Autodial Control:

Use of insect pathogen like Bt formulated The use of an insect species against itself,
product baculoviruses viz. NPV against H. usually through, some means of genetic
armigera, S. liura etc Granulosis virus against modification, to suppress or eradicate its natural
sugarcane stem borer, fungi, Beauveria bassiana population.
against various insect pests in different parts of
the country are under progressive use for last few Autoparasitism:
decades. Thus, historical development of
biological control is in great progress and within A special type of hyper parasitism in
reach. Most diverse research efforts are which the female develops as primary parasitoid,
expanded than ever before in this field. but the male is a secondary parasitoid through
females of its own species.
Important Terms used in Biological Control of
Crop Pests - I Important Terms used in Biological Control of
Crop Pests – II
Accretive Release:
Balance of Nature:
A method of periodic introduction of
biotic agents in which annual early season The natural tendency of plant and animal
liberations against fairly abundant pest populations, resulting from natural regulative
populations allow the beneficial organism processes in an undisturbed environment, to
population to increase naturally in response to neither decline in numbers to extinction, nor
rising pest densities as the season progresses. increase to infinite density.

Agroecosystem:

The modified and simplified system of Biological Control:

plants, animals and habitat used for human
agricultural purposes.
 9

Biological pest suppression in its narrow, A type of parthenogenetic reproduction in

classical sense, usually restricted to the which the progeny of unmated females may
introduction by man, of parasitoids, predators, consist of both males and females.
and/or pathogenic micro organisms to suppress
population of plant or animal pests. Important Terms used in Biological Control of
Crop Pests – III
Biological Insect Pest Suppression:
Ecological Niche:
The use or encouragement by man, of
living organism or their products for the The place an organism occupies in its
population reduction of pest insects. biotic relationships and physical environment as
determined by its particular structural
Biotype: adaptations, physiological adjustments, and
developed behavioral patterns.
A biological strain of an organism,
morphologically indistinguishable from other Economic Threshold:
member of its species, but exhibiting distinctive
physiological characteristics; particularly in A population density concept which
regard to its ability to successfully utilize pest- allows the determination of the point at which
resistant host organisms or to act as an effective pest numbers are sufficient to cause economic
beneficial species. injury unless suppressive action is taken.

Cleptoparasitism: Ectoparasitoid:

A type of parasitism in which the adult An insect parasite which develops

parasitoid preferentially appropriates for its own externally on its arthropod host.
progeny the previously paralyzed and parasitized
host of another parasitoid. Endoparasitoid:

Colonization: An insect parasite which develops within

the arthropods host.
The controlled release of a quality of
biological control agents in a favorable Endotoxin:
environment for the purpose of permanent or
temporary establishment. An toxin substance formed by certain
bacteria and retained within their vegetative cells
Conservation: (e.g. in Bacillus thuringiensis, the endotoxin
occurs as a part of the crystal shaped parasporal
It is the process involved in manipulation body).
of environment to favour natural enemies either
by removing or modifying the adverse effects or Entomogenous:
by providing the lacking pre-requisities.
Refers to organisms (usually micro
Density dependent factor: organisms) growing in or on the bodies of
insects.
Refers to mortality factors or processes in
the environment which destroys an increasing Entomopathogenic:
percentage of the subject population as the
numerical population density increase and vice Capable of causing disease in insects.
versa.
Entomophagous:
Density Independent Factor:
Refers to the consumption of insects or
Refers to mortality factors or processes in their parts, insectivorous.
the environment which destroys a relatively
constant percentage of the subject population
regardless of changes in its density.
Denterotoky: Entomophilic:
 10

Insect-loving. An insect parasite which normally

Enzootic: develops successfully at a rate of two or more
individuals per arthropod host.
Refers to a disease condition (or
sometimes a pest) which is constantly present in Heteroxenous:
an area, but at a low rate of incidence.
Describes a species which require the use
Epizootic: of more than one host species to successfully
complete its annual life cycle.
An outbreak of a disease (or sometime a
pest) in which is an unusually high number of Inclusion Body:
cases (or density of the pest).
The proteinaceous or crystal like
Exotic: structure produced in insect cells infected with
certain viral pathogens. (It occurs in various
A soluble toxic substance produced by shapes and sizes and usually encloses a number
certain bacteria and found in their surrounding of replicated virons).
growth medium.
Indigenous:
Factitious Host:
Native to a particular region or country.
An unnatural but acceptable host used in
laboratory propagation of beneficial organisms. Inundative Release:

Facultative Parasitism: A method of periodic introduction of

biotic agents which is analogous to insecticide
Here in reference to nematodes which treatment in that a greater amount of the
may either parasitize healthy insect, or develop liberated material is used than is actually
in some other way in the environment (e.g. effective repetition m may be necessary and the
mycetophagy) if no insect host is encountered. effect is more less immediate.

Facultative Pathogen: International Unit (IU):

A micro organism which is capable of An arbitrarily set basis for comparing the
growth and reproduction in either a non living efficacy of insect pathogenic Bacillus
medium or living host; in the latter instance, a thuringiensis preparations. It is one thousand of
disease condition of the host may arise. the amounts of insecticidal activity contained in
one million of a preparation of the primary
Fortuitous Biological Insect Pest Suppression: standard E-61 strain B-t., as measured by
bioassay against certain caterpillars e.g. A
The desirable but accidental movement of standard B-t. strain (HD-1-S-1971) has assigned
exotic beneficial organisms to new areas and/or a potency of 18000 IU/mg against the cabbage
new pests, where pest population suppression looper.
eventually results; or the successful population
regulation of exotic pests by indigenous natural IOBC:
enemies.
(International Organization for Biological
Important Terms used in Biological Control of Control of noxious animals and plants an affiliate
Crop Pests – IV for the International Union of Biological
Sciences): A global organization of government
Granulosis: units and individual interested in biological pest
suppression headquartered in Zurich,
An insect viral disease characterized by Switzerland. Major objective include
the presence of minute granular inclusions dissemination of information, coordination and
(capsules) in the infected cells. promotion of research and application of
biological pest suppression. Publisher of the
journal, Entomophaga.

Gregarious Parasitoid:
 11

Important Terms used in Biological Control of lower limits, over a period of time, by a complex
Crop Pests – V combination of all the additive conditioning, and
subtractive processes striking that wild
Life Table: population.

A device for expressing in an orderly Natural Enemies:

fashion, observations on the changing density of
an insect population in time and space and the Strictly, the parasitoids, predators, and
processes which direct those changes, especially pathogenic microorganisms associated naturally
in relation to the age-specific distribution of with a specific wild population of plants or
mortality and its causes. animals, and causing mortality or debility to the
individual thereof; often used in a general sense
Microbial Insecticide: for all parasitoids, predators, and pathogens.

A pathogenic microorganism or its Obligate Parasitism:

products (e.g. toxins) when used by man to
suppress an insect population. Here in reference to nematodes which
must develop parasitically and cannot reproduce
Microbial Pathogen: and complete growth away from.

A microorganism which causes disease in Obligate Pathogen:

its host; more specifically, a term used in
preference to microbial “insecticide” to denote a A disease causing microorganism which
microorganism used by man to suppress insect requires a living host to grow and reproduce.
pest population.
Important Terms used in Biological Control of
Monoculture: Crop Pests – VI

The cultivation of a single crop species Parasite:

over large areas without provision for diversity
or use of the land in any other way. An animal species which level on or in a
larger animal, the host, feeding upon it, and
Monophagous: frequently destroying it. A parasite needs only
one or part of one host to reach maturity.
The term restricted to the use of only one
plant or animal species as host or prey. Parasitism:

Monoxenous: A qualitative term referring to a kind of

symbiosis in which one party (the parasite) lives
Describes a species which requires only a at the expense of the other (the host),
single host species on which it successfully contributing nothing to the relationships and
complete its annual life cycle. frequently destroying the host in the process.

Multiparasitism: Parasitization:

A condition resulting from the A quantitative term referring to the

simultaneous use of a single host individual by proportion of a host population attacked by
two or more species of primary parasitoids. parasites.

Multivoltine: Parasitoid:

Having two or more complete An insect parasite of an arthropod

generations annually. parasitic only in its immature stages, destroying
its host in the process of development and free
Natural Control: living as an adult.

The process of dynamic equilibrium

which maintains the characteristic mean density
of a wild population within particular upper and
 12

Periodic release: Solitary Parasitism:

A method of beneficial organism All insect parasite which normally

introduction which involves repeated liberations develops at a rate of one individual per arthropod
to artificially maintain high population levels of host.
indigenous biotic agents in situations which such Superparasitism:
levels are unattainable naturally.
A condition resulting from the use of a
Polyhedrosis: single host individual by more individual
parasitoids of the same species than it can
An insect viral disease characterized by successfully sustain to maturity because of
formation of polyhedron shaped inclusions in the nutritional limitations.
infected cells. The disease is known as a nuclear
Polyhedrosis or nucleopolyhedrosis. Symbiosis:

Polyphagous: The living together in close association of

two or more species of organisms.
Adapted to the use of wide variety of
plant or animal species as hosts or prey. Thelyotoky:

Population Dynamics: A type of parthenogenetic reproduction in

which only female progeny are produced.
The study of numerical changes in
populations of living organisms in time and Tolerance:
space and of the processes which cause such
variations. According to Painter (1951), it is the
basis for resistance in which a host shows an
Predator: ability to grow and reproduce itself, or to repair
injury, despite supporting a pest population equal
An animal which feeds upon other to that damaging a more susceptible host.
animals (prey) that are usually smaller and
weaker than itself, frequently devouring them Trap Crop:
completely and rapidly. A predator most often is
required to seek out and attack more than one A small planting of a susceptible and
prey to reach maturity. highly attractive host, planted early in the season,
or removed in space from the main crop, in order
Primary Parasitoid: to divert attack and infestation by pests and
allow for their easy destruction.
An insect parasite of any arthropod which
is not itself parasitic. Virulence:

Protelean Parasite: The disease producing power of a

microorganism, i.e. the relative capacity of a
An insect species in which only the microorganism to invade and injury the tissues of
immature stages are parasitic. its host.

Secondary Parasitoid:

An insect species of a primary parasitoid.

Septicemia:

A morbid condition caused by invasion

and multiplication of microorganisms in the
blood.
 13

Important Natural Enemies and Their Hosts food. They catch them directly or with the help
of various types of snares made out of webs. The
Biological insect suppression in its important species found actively feeding on
original or classical sense involves the directed sugarcane pyrilla in India are Clubiona atwali
use of beneficial organisms. These beneficial and Clubiona drassodes be to the family
organisms fail into several categories or groups. Clubionidae.
The broad-based categories of biological control
agents/natural enemies are (according to function 2. Mites:
involved).
Many mite species have acquired a
1. Parasites and Parasitoids parasitic life on insect pest, Allothrombium spp.
2. Predators lives as an ectopara site on many small insects
3. Micro-organisms and Entrombidium spp. on egg of locust and
grass hoppers.
On the other hand, the categorization may also be
done as: 3. Insects:

1) Vertebrates: These include predatory animals Insects form the single largest and the
like: most important group of predators and parasites.
They suppress population of known or potential
A) Fishes (Pisces) pests. They belong to 15 orders and more those
B) Amphibians (Amphibia):- Tadpoes, 240 families. Spraying mantids devour a large
frogs, toads etc. number of insects of all sorts. The green lace
C) Birds (Aves):- King crows, Starling, wing, Chysoperia spp. feed voraciously on
Quail partridges, Mynah, House crow, aphids and other soft bodied insects @ 160
Indian roller. individuals per day. Tiger beetle, Cicindela spp.
is very common in Northern and Western India.
D) Mammals (Mammalia):- Bats, mice, The lady bird beetles form a group of predators
Snakes, Lizards, Squirrels, Mongoose of aphids in the larval stage as well as in adult
stages. The vast majority of the parasites belong
2) Invertebrates: (Arthropods) to Hymenoptera, Diptera and Strepsiptera orders.
Trichogramme spp. which are more or less
A) Predators: Spiders, Mites, Hydra, universal parasites of eggs of Lepidotera.
Planaria.
Parasite, Protelean Parasite and Parasitoid
B) Parasites: Arthropod parasites, Insects.
Parasite:
3) Namathelmithes: Nematodes
An animal species which lives in or on a
4) Protozoan: - Protozoa. large animal, the host, feeding upon it and
frequently destroying. A parasite needs only one
5) Pathogenic microorganism: Bacteria, Viruses, or part of one host to reach maturity.
Fungi.
Protelean parasite:
All or most of these categories have
yielded successful examples of insect pest An insect species in which only their
suppression, either single or in concert. Among immature stages are parasite.
these natural enemies, from the point of view of
biological control three groups of arthropods are Parasitoid:
important i.e.
An insect parasite an arthropod, parasitic
1. Spiders only in its immature stages, destroying its host in
2. Mites and the process of its development and free living as
3. Insects. an adult.

1. Spiders: A parasitoid as a particular kind of

Protelean parasite that attacks invertebrate hosts
The spiders universally live a predatory which are nearly always destroyed in the process
life and are constantly look out for insect as their of development.
 14

1. A parasitoid restricted to attack and 5. Adaptation to broad range of climatic

destroys only arthropods, rather than conditions.
invertebrate in general. 6. The parasite species should be
amenable to culture in the insectory.
2. Parasitoids have been used more 7. It must be efficient to bring about the
frequently than insect predators in death of the host.
classical biological insect pest 8. It should not become a plant feeder
suppression programme and probably in under any conditions.
ratio from 2:1 to 4:1. 9. It should not be hyperparasites or
harmful to the beneficial species.
3. The parasitoids differ from true 10. Good parasite must complete with
parasites in many ways. other species of natural enemies successfully for
occupying food, space and shelter and must
4. The development of individual destroy the pest population within short time
destroys its host. even at high host density.
11. There should be synchronization of
5. The host is usually of the same life cycles of the parasite and the host.
taxonomic class.
Taxonomic Relationships of Parasitoid
a. In comparison with the hosts
they are of relatively large size. Sweet man (1936) recorded different groups of
b. They are parasitic as larvae parasitoid belonging to 5 orders containing 86
only, the adults being free living forms. families with insect hosts. Orders in which
parasitoids recorded are Coleoptera, Diptera,
c. They do not exhibit heteroecism. Hymenoptera, Lepidoptera and Strepsiptera.
d. As a parameter in population dynamic However, in order of importance order
their action resembles that of predators Hymenoptera (wasps) and Diptera (flies) are
more than that of true parasites. mostly used in biological insect pest suppression.
Order Hymenoptera contains roughly 2 to 5 lakh
Insect Parasites and Ideal Characteristics of species of parasites. Townes (1972) estimated
Parasites that only about 5% of the parasitic species had
been described and of these numbers, the
Insect Parasite: biological information was available on approx
for only 3% species. In classical biological insect
Parasitic insect are those which live in pest suppression programmes, the parasites
close association with other living organism predominantly used belong to super families
called the ‘host’, from whom it derives the Ichneumonidae, Braconidae and Chalcidoidea.
material essential for the existence without
conferring any benefit to it (host). The Ichneumonidae usually include the
largest of the beneficial wasps associated with
Ideal Characteristics of Parasites: host larvae and pupae. The Braconids on the
average are usually much smaller than the
1. The parasite should have high Ichneumouids. The Diptera ranked next in
searching capacity of host and utilize the host. importance to Hymenoptera in biological insect
pest suppression programmes. The families of
2. It should be fairly host specific in Diptera exclusively parasitic are cytidae,
feeding rather than polyphagous i.e. restriction Nemestrinidae, Pipunculidae, Conopldae,
in feeding habit to a relatively few species. This Pyrgotidae and Tachinidae, as well as
implies high degree of adaptation. Bombylidae.

3. It should be primarily to its high Classification of Parasitoids on the Basis of

potential reproductive capacity, ultimately high Biological Relationships – on the Basis of
fecundity i.e. potential for rate of increase. Stage of Host Attacked

4. Ability to occupy all the host inhabited a) Egg Parasitoid:

niches and to survive well.
The true egg parasitoids are those
individuals that deposit their eggs in and whose
 15

progeny emerge from the host eggs. Designed as e.g. Epipyrops fuliginosa on nymphs of
‘E’ e.g. Trichogramma chilonus, T preteosum, Idioscopus clyealis.
Ooencyrtus sp. a true egg parasitoids of various
lepidopterouspests. i) Nymphal Adult Parasitoids:

b) Egg Larval Parasitoid: The parasitoids deposit their eggs on/in

host nymph and emerge from the dead adult host.
Another category of egg parasitoids, Designated as ‘NA’ e.g. Epiricania melanoleuca
which deposits eggs in the host eggs but parasitic on Pyrilla perpusilla.
development and emergence are not completed
until the host larval stage is reached. Designated Classification of Parasitoids on the Basis of
as ‘EI’ e.g. Braconid, Chelonus annulipes on Parasitoid - Host and Parasitoid – Parasitoid
European corn bore, Chelonus blackburni on Relationships
PTM and bollworm, Capidosoma koehleri on
PTM. I) Number of Individuals/hosts:

c) Egg Pupal Parasitoids: a) Solitary Parasitoids:

If egg parasitoids deposits egg in the host One progeny alone is capable of
eggs and emerges from a host pupa it would be competing the development in or its host
designated ‘Ep’. e.g. Chelonus blackdurni on PTM.

d) Larval Parasitoids: b) Gregarious Parasitoid:

True larval parasitoids are those Several progeny are capable of

parasitoids which deposit egg on the larvae and completing their development in or on a
their progeny complete development and emerge single host e.g. Copidosoma koehleri on
from the host larvae. Designated as ‘L’ e.g. PTM. This may includes the parasitoid that
Apanteles spp. On pink bollworm, Bracon deposits one or very few eggs in their host from
brecicornis on spotted boll worms. which develops hundreads or thousands of
progeny. These are polymbryonic species e.g.
e) Larval Pupal Parasitoids: Braconid, Macrocentrus gifuensis on
European corn borer.
The parasitoids those deposit their eggs
on or nearhost larvae and emerge from host II) Site of Attacks on Host Body:
pupae. Designated as ‘LP’ e.g. Pleurotropis
epilachnae on Epilachna spp. a) Ectoparasitoids:

f) Pupal Parasitoid: An insect parasite which feed

externally on the host body and complete their
Parasitoids that deposit their eggs in the development externally on its host e.g. Bracon
host pupae and emerge from the host pupae. brevicorni.
Designated as ‘P’ e.g. Brachymeria nephontidis
on Earias spp. All chalidae (Hymenoptera) are b) Endoparasitoid:
pupal parasitoids.
Parasitoids which complete their
g) Adult Parasitoids: development within or inside their host body e.g.
Chelonus blackburni. Endoparasitoid of aphids
Parasitoids of adults hosts. The frequently emerge through a flap cut in the
parasitoids deposit a larva on its host while in host abdomen.
flight and the mature maggot emerges from the
dead adults host. Designated as ‘A’ e.g. III) Food Web Relationships:
Blaesoziphae kellyi a parasitoid of locust.
a. Primary Parasitoids:
h) Nymphal Parasitoids:
The form of parasitism in which
The parasitoids deposit eggs on nymphs the attacking organism that develop itself in
and their progeny complete development and or upon the host which is non-parasitic e.g. on
emerge from the host numphs. Designated as ‘N’ introduced pine saw fly 24 parasitoids of a
 16

primary nature from hypmenoptrous and b) Monoxenous:

Dipterous species.
The parasitoids those require only
b. Secondary Parasitoids: one host species for development, e.g. Exenterus
amictorius a parasitoid on the introduced pine
The parasitoids develop itself in saw fly and the Drino bohemica, a lachinid
or on the host that are primary parasitoid. parasitoid of European spruce sawfly.

c. Tertiary Parasitoids: Hyperparasitism

The parasitoid develops itself in The phenomenon of Hyparasitism occurs

or on the host which is already secondary when parasite attacks and develops on another
parasitoid. e.g. The parasitoid Tetrastichus parasite. There are several degrees of
coerulescens parasitic on secondary parasitoid hyperparasitism which depend on the food chain
Hybrocytus spp. and the primary saw fly as host primary, secondary, tertiary and so on.
parasitoid Itoplectis conquisitor.
A hyperarasitoid is parasitoids which develop on
d. Quaternary Parasitoids: another parasitoid i.e. a parasite of a parasite.

Form of hyperprasitism in which

the parasitic establish itself in/or the tertiary
parasitoid. E.g. pea aphid Acyrthosiohan pisum
------------Primary consumer
IV) No. of Hosts Attacked: Polyphagous pest
a) Monophagous: Primary parasite Aphidius sinithi
------------Secondary consumer
The parasitoids which are specific
to one particular host e.g. The icheumonid Secondary parasite Allaxysta vitix
parasitoid, Mesolicus tenthredinis is a specific -----------Tertiary consumer
for saw fly. Tertiary parasite Asaphes califonical
-----------Quaternary parasite
b) Oligophagous or Stenophagous:
It is the policy in biological control to prevent
Those parasitoids that restrict the introduction of secondary parasites. The
themselves to vary few and often closely related hyperparasites can be eliminated or retarded by
hosts, e.g. Exerterus amictoriius is an use of differential insecticides. There is belief
ichneumonid parasitoid of saw fly in the genera that hyperparasites are usually less
Diprion and Neodiprion. discriminating than primary parasites I their
selection of hosts. As introduced hyperparasites
c) Polyphagous: is likely to find all suitable niches occupied than
native through competition. Hyperparasites
Those parasitoids that maintain already present in a region may have in some
themselves on a multiple of hosts, e.g. cases prevented or at least delayed the
Compsilura concinnata a tachinid introduced establishment of introduced parasites.
against gypsy moth has been recorded from The hyperparasites play an important part in the
close to 20 hosts. maintenance of the balance between insect
species in nature that is the aspect of population
V) No. of Host individuals Essential for dynamics.
Attack:
Superparasitism
a) Heteroxenous:
The condition resulting from the use of a single
Many of oligo and polyphagous host individual by more number of individual
parasitoid species requiring alternating of hosts parasitoids of the same species than it can
to complete several generations each year, e.g. successfully switch to maturity because of
The tachinid, Ceromasla auricaudata which over nutritional limitation. This occurs with solitary
winters in a host pupa of fall webworm normally endoparasites, physiological suppression of the
attacks univoltine spruce budworm in the spring super numeracy larvae or eggs results in the
 17

survival of a dominant individual. In some cases, 4. Multiple introductions increase the chances of
however, host itself succumbs prematurely obtaining a gives species which will attack more
before the super numeracy parasites are than one host in the new environment. This
eliminated and all perish. enables the natural enemy to overcome
difficulties of host scarcity which might occur if
The many parasitoids usually are the progeny of only one host were involved. Multiple
multiple attacks by different individual adult introductions of new natural enemies is accepted
females, e.g. the larva of the introduced pine saw as a policy and undertaken the effect of
fly, each of which may carry several macrotype competition between the established and the
eggs of a tachinid, Diplostichus lophyri. Though newly imported natural enemy again assumes
all eggs may hatch and the larvae penetrate the importance. This does not cause detrimental
hosts integument only one will survive to the effect but the host population balance.
adult stage. When an individual host is
parasitized by more than one larva of a single Types or Forms of Multiple Parasitism
species, but all survive, this is either gregarious
or polyembronic parasitism. In some cases, when 1) Cleptoparasitism:
hosts are few or when the parasite fails to find
unparasitized hosts, super parasitism does occur. The phenomenon in which a parasitoid
prefentially attacks on a host that are already
Multiple Parasitism and Advantages of parasitized by and other species of parasitoid is
Multiple Parasitism called Cleptoparasitism e.g. The cleptoparasitic
habitat of Eurtoma pini on European pine shoot
Multiple Parasitisms: moth. E pini females ovipositor only on shoot
moth larvae that had been immobilized
It refers to that condition in which previously by primary parasitoids.
individuals of two or more species of parasitoids Cleptoparasitism is not hyperparasites for it does
occur simultaneously or on the same single host not parasites the previously occurring parasite
at the same time. In most cases, only one of these species. Instead multiple parasitisms are
species survives to maturity. In rare cases, (e.g. involved and relationship between the species is
Trichogramma species) more than one species competitive with cleptoparasite usually
may complete their development. dominating.
The condition of multiparasitism generally
results in the death of one of the individuals 2) Autoparasitism or Adelphoparasitism:
through one or other mortality factor, but not
through hyperparasitism. Many of primary The phenomenon in which a species of
tachinid parasitoids of the spruce budworm parasitoid is parasite upon itself is termed
compete with ichneumonid parasites. The adelphoparasitism. In this case parasitoids use
multiparasitism results in direct competition for their own species as a host to develop some of
food between the parasite larvae so that usually their progeny. Aphelinid species with this habitat
one fails to mature. occur in genera Coccophogus e.g. Coccophagus
scutellaris (the male of which is an obligate
Advantages of Multiple Parasitisms: parasite of the female).

1. A series of parasites which live in the same Few other Bases of Classifying the Parasitism
habitat but attack a sequence of host stages is
advantageous because environmental variations Besides the above bases of classification
which adversely affect one species may favor of parasitoids few other bases of classifying the
another and total host mortality should be parasitism are as given below:
greater.
1) Phytoparasitism:
2. When several parasite species are established
on a common host, these will usually be broader The plant parasitizing/developing on
habitat coverage. other plant e.g. striga on jowar.

3. Past records indicated that multiple species a) Zoo parasitism:

introduction improved the results of parasitizing The insect as an animal
and pest population regulation and rarely occur parasitizing on other animal species e.g.
detrimental effects. mosquito on human beings.
 18

2) Position of feeding: 5) Based on intensity of attack:

a) Simple parasitism:
a) Ectoparasitism: Form of parasitism resulting from
The parasitic species feeding a single attack on hosts.
externally on its host. b) Superparasitism:
Parasitism of a individual host by
b) Endoparasitism: more larvae of single parasitic species
The parasite punctures the host that can nature in the host e.g. Bracon
cuticle and enters and feed inside the host kirkpatiriki.
body. c) Multiple parasitisms:
3) Sequence of attacks: It is a parasitism in which a single
host is attacked by two or more types of
a) Primary parasitism: parasites.
Form of parasitism in which the
attacking organism established itself 6) No. of host species attacked:
in/on the host which is not parasite. a) Monophagous:
Only one host is attacked by a
b) Hyperparasitism: parasite.
Form of a parasitism in which b) Oligophagous:
parasites attack on other parasites. Only two or few more type of
host, those are closely related are
c) Secondary parasitism: attacked by parasite.
Form of a parasitism in which c) Polyphagous:
parasites are attacking on the host which Parasite has more than two hosts
is already a primary parasite. to be attacked.

d) Tertiary parasitism: 7) No. of host individuals essential for attack:

Form of hyper parasitism in a) Monoxennous:
which the parasite established itself in/on The form of parasitism in which
the secondary parasite. only one host is necessary to complete
the development of parasite.
e) Quaternary parasitism: b)Heteroxenous:
Form of hyperparasites in which
the parasites establish itself in/on the Form of parasitism in which
tertiary parasite. different type of hosts is required for
complete development of parasite.
4) Adoption and necessity:
8) Based on number of parasites in/on host:
a) Obligate parasitism: a) Solitary parasitism:
Parasite is limited to parasitic Form of parasitism parasites in
existence only. Here in reference to which on single parasite feeds and
nematodes which must develop develop in/on the host.
parasitically and cannot reproduce and b) Gregarious parasitism:
complete growth away from the host. The form of parasitism in which
number of individuals of one species
b) Facultative parasitism: develop in/on the host.
Parasite occasionally adopts itself
either to parasitic nature of free life. 9) Permanency of attack:
Here in also reference to nematodes a) Permanent parasitism:
which may either parasites healthy Form of parasitism in which the
insects or develop in some other way parasites complete entire active life cycle
in the environment. as a parasite.
b) Periodical parasitism:
c) Incidental parasitism: Only one stage of a parasite is
Form of parasitism in which completed as parasite.
parasite establish itself on host in which
it is not ordinarily associated with host.
 19

Insect Predators g) Larvae usually elongate with gradually

tapering bodies. The body regions are
Definition of Insect Predators: distinct and colored with blue,
black or orange. They appear warty of
The predator is defined as “an animal which spiny dorsally.
feeds upon other animals (prey) that are usually
smaller and weaker than itself, frequently 2) Carabids:
devouring them completely and rapidly” (Copple
and Martins, 1977). A predator most often is The ground beetles (Coleoptera: Carabidae)
required to suck but an attack more than one prey a) The beetles through predominantly
to reach maturity. black have some brilliantly colored in
metallic greens, blues or purple.
Distinguishing Characteristic of an Insect b) Most species have broad elytra, narrow
Predator: pronotum and a still narrower head.
c) They range from 2-25 mm in length.
1. Generally it consumes more than one host d) The legs are long allowing for rapid
individual. movement.
e) The antennae are attacked between
2. Most insect predators move around freely in eyes and mandibles on each side of head.
both their immature and adult stages while f) The larvae are slightly flattened and
searching for and feeding on their prey. slender tapering towards the posterior end
which bears two spine like
3. Though many of the predators are larger than processes. They have chewing type of mouth
their prey, in some instances adult parasitoids parts.
may act like insect predators by feeding on and
killing the host. 3) Crysopids:

4. Predatory insects feed on all host stages, egg, The green lace wings (Neuroptera: Chrysopidae)
larval or nymphal, pupal and adult. a) These are slender bodied insects.
Colored in a delicate green with golden eyes.
Taxonomical Relationship of Insect Predators b) Antennae are long and slender.
c) Forewings are almost equal in size
Sweetman (1936) recorded about 14 Orders with with green veins which fork profusely near wing
167 Families for predatory insect representatives. margins.
He further added in 1950, 2 more orders and d) The adults of some species and all of
some 42 families. The orders Coleoptera, the larvae are predacious.
Neuroptera, Hymenoptera, Diptera and e) The spindle shaped larvae
Hemiptera contain families that so far have been called”aphid-lions” have powerful sickle shaped
of major importance in biological insect pest mandibles. The legs are
suppression. Greatest numbers of predatory slender and hairy and body is provided with a
species occur in order Coleoptera. The order row of spine bearing tubercles along
Odonata is exclusively predaceous. each side Aphid-lions are usually mottled
with grey, yellow, green red or
Taxonomic Characteristics of Important black.
Predatory Insects:
4) Formicids:
1) Predaceous Coccinellids:
The ants (Hymenoptera: Formicidae)
The lady bird beetles (Coleoptera; Coccinelidae). a) These are social insects. Many
a) The adult beetles have bright body in displaying polymorphism.
various shades of red, brown, tan or even b) They have chewing type of mouth
black. parts.
b) Usually they are spotted. c) The antennae are strongly elbowed
c) They range from 2-6 mm in length and with a very long first segment.
are hemispherical in shape. d) Body segments are distinct and thorax
d) The head is small with chewing type is slenderest region. The gaster or
of mouth parts. swollen part of the abdomen is attached
e) The antennae are short and elevate. to the thorax with a short slender
f) Tarsi 3 segmented. petiole bearing one or two projectious.
 20

The predator feeds on their prey

5) Syrphids: by sucking the juice from body, e.g. Assassin
The entomophagous syrphid flies (Diptera, bug, Reduviidae, lacewing larvae. Chrysopidae,
Syrphidae) Syrphidae, Prentatomids. These insect often
a) They are predators only in their larval injects a powerful toxin which quickly
stages. immobilizes the prey so that the feeding
b) Adults are diverse in form, some process is placid affair with little thrashing
slender and some broad and their bodies are about by the victim. For example once a
polished black or metallic blue or lacewing larvae clamps its sickle mandibles
green with prominent yellow bands, into a caterpillar several time its size, the
spots or hairs. caterpillar is doomed and its period of struggle
c) They are 3 to 25 mm long and are lasts but a few seconds.
separable from others Dipters by the
presence of spurious wing vein
between radius 4+5 and media 1+2. 2) On the Basis of the Specificity of Host
d) The green or tan larvae are elongate, Relations:
legless maggots with pointed sucking
mandibles. Thompson (1951) referred to the fact that
predators have a full complement of sense organs
6) Mirids: and can perceive their prey at a distance. There
was a high degree of host specificity. The
The plants bugs (Hemiptera: Miridae) importance of olfactory response and visual
a) The plant bugs contain many stimuli prey location is also elaborated.
predaceous species.
b) Adults are 2.5 to 6 mm long, velvety in a) Monophagous:
appearance and often highly colored.
They have cureus and 1-2 large The predator which is highly host
cells in the membrane of fore wings, both specific and consume exclusive on a single
rostrum and antennae 4 species of prey, e.g. Rodolia cardinalis is a
segmented and no ocelli. specific predator of cottony cushion scale
c) The body is elongate oval and often (Icerya purchasl).
clothed with fine hairs. The hemelytra are
longer than abdomen and b) Oligophagous:
prevailing colors are combinations of green,
black or red with spots or stripes The predators with restricted host
of black, yellow, white or red. range feeding on more than one host preys of the
d) Mirids have sucking type of mouth closely related species, e.g. Syrphid larvae feed
parts. only on aphid species.
e) Metamorphosis is incomplete and
nymph is predaceous. c) Polyphagous:

Biological relationships Insect Predators The predator’s species feed on a

wide a range of prey, e.g. preying mantids,
Host-predator Relationships: Prentatomids, ants, ground beetles etc.

1) On the Basis of Type of Feeding (type of 3) On the Basis of Morphological

mouth parts): Adaptations:-

a) Chewing Mouth Part: Many species have special morphological

or biological adaptations to make them effective.
The prey is consumed with use of
chewing type of mouth parts, e.g. preying a) Preying Mantids: They have grasping
mantids, ants, coccinelids, ground beetle, lady and holding forelegs as well as large eyes and on
bird beeltles, carabids. They simply chew extremely mobile head to assist in location and
up and bolt down there victims – legs, bristles, capture their prey.
antennae and all.
b) Dragon Flies: Larval dragon flies
b) Sucking Mouth Parts: have specialized mouth parts to capture
aquatic prey and adult dragon flies are
 21

excellent fliers and able to catch their prey on population in balanced condition in 12th century.
the wing. Their food consists of stages of Lepidopterous
caterpillars. This is an example to be quoted for
c) Adult Carabid Beetles: They have efficient facultative predator. The mired
long legs, move rapidly to run down their Cyrtorhinus modulus has been proved as an
prey. effective predator on the eggs of the sugarcane
leaf hopper. Its first release was made in 1920
d) Ant Lion: Larvae settle in their from Australian stock and late from Fiji and by
specially constructed pits awaiting on 1923 the sugarcane leaf hopper was suppressed.
unsuspecting prey.

e) Ants: They utilizing their social habits

assist each other in capturing and moving 1) Vedalia beetle, Rodolia Cardinalis Mulsant
prey to their nests.
(Coleoptera: Coccinelidae) This is probably the
f) Wasps: They often paralyze their prey most frequent mentioned predator in classical
with a venomous sting and provides food for biological control literature. It has been
their developing brood. thoroughly reviewed by Debauch(1974). The
successful story of the Vedalia beetle against
g) Syrphid Flies: Adults may deposit cottony cushion scale, Icerya purchasein
their eggs directly among aphids so that California on citrus has already been outlined in
food is immediately available to newly C. V. Riley campaign. Like success in California,
maggots. it has been repeated in 30-50 countries around
the world where this beetle has been released.
h) Coccinellid Beetle: The hemispherical
shape and slow movement in a colony of Adults of Vedalia beetle male and have a pre-
their prey do not disturb the feeding ants and oviposition period of 3-4 weeks in the summer
allow the predators to continue feeding. and 1-3 weeks in the winter. The eggs are laid
e.g. lady bird beetle. singly or in small cluster. Oviposition lasts on as
average of 75 days (11-170 days) and the
i) Stink Bugs: With their powerful average number of eggs laid by a female is 341
sucking mouth parts they are able to withdraw eggs. The females deposit eggs on the egg sacs
body fluids from their prey while it is of their prey. The predatory eggs hatch in 6 days.
suspended in the air. Larval stage lasts for 22 days, during which it
moults 4 times. Pupal stage lasts for 8 days. The
On the Basis of Competition within and total life cycle from egg to adult is completed on
Between Predator Groups: an average of 35 days. The adult female live for
an average of 70 days and adults males 81 days
Cannibalism: and it completes 6-7 generations per year. The
larva and adult eat cottony cushion scales. The
It occurs when on species feeds on others of its mated egg producing female eats more prey than
own kind. This rarely occurs in nature, but it virgin females or males.
would have an advantage for species survival in
the absence of alternate food. Under laboratory 2) Cryptolaemus montrouzieri Mulsant
condition of crowding and limited food supply
cannibalism can occur readily. Some coccinellids (Coleoptera: coccinellidae) The mass production
just after emerging from their eggs may feed on and periodic release of C. montrouzieri against
unhatched eggs in the same cluster. Lacewings various mealy bugs pests of citrus has been
utilize stacked eggs to prevent such cannibalism going on for several years. The major pest
or perdition by other species. against which it is employed is the citrus mealy
bugs Planococcus citri and grape vine mealy
Some Important Insect Predators bugs Maconellicoccus hersutus. The life cycle of
C. montrouzieri takes about 30-35 days at
The first known use of the tactic of temperature between 23 and 26.7 ̊C. Colonies of
biological insect pest suppression was in china 30-40 adult coccinellids may be placed in each
around 300 A.D. where in ants were used to tray when mealy bugs are 8 days old. They
protect orange groves from developing wormy deposit their eggs on the sprouts and trays. After
fruit. The red wood ants are considered 12 days, their adults are removed for liberation.
important in maintaining forest insect pest As predator larvae feed and mature, seek
 22

pupation site 18 days after the parent stock is

removed their adult progeny first appear. The 3 Pupal stage 7 days in rainy season
emerging beetles are collected for about 21 days.
Adults can be hold in the vials for 12-18 hours
7 to 10 days in summer
prior to release if cooled to 15.6 ̊C. The adult
predator beetles are released at approximately 20
adults/citrus tree. 10 to 15 days in winter
season
3) Green lacewing:
4 Adult stage 30 to 35 days in rainy
Chrysoperla carnea
35 to 50 days in winter for
(Neuroptera : Chrysopidae) This is one of the both males and females.
most important chrysopid in biological insect
pest suppression programmes. The eggs are 5 Fecundity 200 eggs to 700 eggs.
characteristically stalked and take an average of
9.5 days (7-15 days) to hatch. The newly
emerged larvae carry no reserve of foods and Desirable Attributes of Bio-agents
thus must crawl down the stalk and began to
search for pray immediately. The larvae develop The classical practice of introduction exotic
through 3 instars in 12-28 days. The pe-pupal beneficial organisms or pest suppression is the
and pupal stages lasts for average of 19.2 days only useful method under restricted conditions.
(11-21 days) and 6-48 days, respectively. The While introducing beneficial organisms, the
total period from egg to adult is 37-70 days. The concern of the desirable attributes of a natural
pupa emerges from the cocoon and shortly casts enemies and a consideration of some basic
its skin to become an adult. Mating takes place ecological principal have bearing as success or
shortly after adult mergence and repeated failure of biological pest-suppression
copulation is necessary for continuous programmes.
reproduction. The females capable of laying 500-
700 eggs. The number of annual generations Desirable Attributes of Natural Enemies:
range from 2-7. Winter is usually passed in
protected situations by the adult stage. The adult In order to search for efficient beneficial
feeds on aphids and other small insect. The organisms for use in biological insect pest
larvae feed nearly all gardens certain ignite, and suppression it requires some idea beforehand that
eggs of thrips, moths, leaf hoppars etc. what we are seeking. Before introducing new
natural enemies from exotic locations or
analyzing those species which are already
Species: present for same way of augmenting their
usefulness we must know their characteristics of
(i) Chrysoperla carnea and species to display it an efficient regulatory
relationship with the pest. Thus proper selection
(ii) Mallada beninensis of natural enemies of insect is an important part
of success of Biocontrol.

The Organisms should Possess Following

Sr.No. Stage Duration Attributes:

1 Egg period 3 days in rainy season and 1) Ecological Compatibility:

summer season
It is usually important to seek species whose
5 days in winter season ecological requirements are similar to those of
the intended target insect. Parasitoids are
2 Larval stage 7 days to 10 days in rainy frequently limited in effectiveness and have
and summer season greater sensitivity to cold; desiccation, heat etc.
and hence it is of great consideration for parasite
species to withstand such condition suitable for
10 to 17 days in winter
the host. Disparity in ecological responses may
season
be an important limiting factor in the
effectiveness of native beneficial organisms and
 23

an environment manipulation of same sort may high reproductive potential and good searching
make them successful regulative agents e.g. high capacity, but it case of successful biological
humidity by irrigation for development of control full utilization of former factor rarely
pathogenic fungi against alfalfa aphids. comes into play because of low pest densities
and efficient searching ability becomes the
2) Temporal Synchronization: primary characteristic because it maintains those
low densities.
The pest and its natural enemies should be in the
same place at the same time and also their life 6) Dispersal Capacity:
cycles must be synchronized for adequate
regulation to be possible. Thus the reproductive The ability of an introduced beneficial species to
stage of a successful egg parasitoid must be easily and rapidly expand its sphere of influence
active at the time of the hosts egg in every in space to coincide with that of the host is
generation of the host. The efficacy of poorly closely tied to its searching capacity and ecology
synchronized organism may sometimes be adaptability. Most good biological control agents
improved. The practice of periodic inundative shop high dispersal capability, season ends the
release of beneficial insects is another way of pest migrates and natural enemy should also
artificially synchronizing the occurrence of ingrate.
parasitoid and host e.g. release of Trichogramma
spp. 7) Host Specificity and Compatibility:

3) Density Responsiveness: A parasitoid or predator which is monophagous

or silently Oligophagous indicates a high degree
The most desirable biological control agents of biological adaptation to the host and probably
should exhibit positive rapid density a greater degree of direct degree of direct and
responsiveness. Proportion of natural enemy of rapid responsiveness to density changes in the
pest should be maintained. Generally natural population of the target host. Host specificity is
enemies have short life cycle, whereas pest has closely ties with compatibility that is the degree
long life cycles. A strong functional response of biological adaptation. Monophagous
refers to within generation behavioral activity of entomophagous have usually evolved a high
the individual parasitoid or predator in increasing degree of adaptation to the defensive
its attacks against increasingly numerous hosts or mechanisms of their host/prey. Predator with
prey, on the other hand, numerical response polyphagous nature will do the purpose.
refers largely to a multigenerational reproductive Compatibility refers to combination of unnatural
increase by the organism in response to enemies. Likewise lady bird beetles should not
increasing host density. A rapid and strong eat Trichogramma spp.
numerical response characteristic is the most
important attributes of a successful agent of pest 8) Food Requirements and Habitats:
mortality.
This attributes is another consideration in
4) Reproductive Potential: choosing a potentially useful beneficial
organisms. For sustenance of natural enemy
One important factor in the display of density some sort of food should be available to natural
responsiveness is high reproductive capacity enemy like pollen, Honey etc. and also shattering
through either short generation time, high places. Nutritional requirement of natural
fecundity or both. In most cases, the parasitoid or enemies should get fulfilled. Habitat refers to
predator is searched with an innate potential for sheltering places and they should be available for
increase greater than that of the host/prey. natural enemies.

5) Searching Capacity: 9) Hyperparasitism:

The ability to find host/prey at low density has This is a negative attribute to be avoided in
significant bearing on the long term success of selecting Biocontrol agents. To eliminate
organism in the more stable situations. A secondary parasitoids under certain situations
beneficial organism which can successfully Hyperparasitism is most important one.
utilize low density population and reduce its
number through efficient searching behavior is a 10) Culturability:
desirable key regulative agent to be sought. A
true ideal beneficial insect would possess both
 24

This is an important attribute indicating ability of This includes the pathogenic fungi enter
organism which can be mass reared under their hosts through the outer integument of the
artificial condition for large scale release insect body. They are more subject to regulation
programmes. Hence the introduced species must physical factors in the environment since their
be an enable to laboratory culture. penetrative stage generally are not very resistant
to adverse effects of external condition.
Possibilities of using pathogens in bio-control:

Sr.No.
Particulars Pathogens Host

1 Bacteria a) Bacillus Japanese beetle

popilliae causing
Role of Bacteria, Fungi, Baculoviruses and milky disease
Nematodes in Biocontrol of Crop Pest
b) Baculoviruses Lepidopterous
The term ‘Microbial control’ was first thuringiensis pest
used by E. A. Steinhaus (1949) to express the
pest population management through disease 2 Viruses a)Baculoviruses Lepidopterous
causing micro-organisms. Microbial control (br) pest
includes all aspects of utilization of micro-
organisms or their by-products in the control of b) Granulosis Mosquitoes,
pest species. In nature, micro-organisms like viruses (Gr.) mites etc.
viruses, bacteria and fungi, protozoa and
rickettsiae may perform important roles in the c) Nuclear Lepidopterous
dynamics and natural regulation of insect and Polyhedrosis pest
mite population. Virus (NPV)

Definition: 3 Fungi a) Polymycetes Lepidopterous

pest, beetles,
“Microbial control is a phase of aphids, scales,
biological control concerned with the mites etc.
employment of micro-organisms for the control
and reduction of number of animals/plants in a 4 Protozoa Nosema locustae Grasshopper,
particular area/given population”. orthoptera

The study of such organisms has been Neogregarires Flies

included under ‘Insect Pathology’ which is a
broad-based discipline concerned with the study
5 Rickettsiae Rickettsiella Wood wasps,
of all aspects of insect diseases as reflected in popilliae Mosquitoes
any abnormal physiological process or condition
in any insect. Insect pathogens may be divided
6 Nematodes a) Steinernema White grubs
into two groups according to the means by which
spp.
they enter and infect their hosts:

1) Through Ingestion: b)
Heterorahbditus
spp.
It includes bacteria, viruses and protozoa
which must be ingested along with food for
causing infection and mortality and can be The successful use of disease for insect
considered similar to chemical insecticides act as control depends upon the biology and
stomach poison. The viruses are queue specific characteristics of the host insects and the
in their site of development and they multiply pathogenic micro-organisms as well as the
only in certain tissues within the body of the environment. Host insect must occupy the
host. Others, including bacteria may fill their habitats suitable for introduction of a pathogen
hosts purely by the activity of toxins which they and they must have habits that enhance the
produce during growth. possibilities of infection. Since disease is
generally considered as density dependent factor
2) Through Integument: of mortality the insect that live in aggregation or
 25

which form large populations are more situation where insecticides have become
susceptible to epizootics as compared to the ineffective due to pest resistance.
species which maintains low population
densities. 6) Conventional Techniques/Methods for
Application: The microbial pathogens are
The major emphasis in the application of highly versatile in so far as the method of their
microbes has been to field collect or artificially application is concerned. The method of
mass culture a specific insect pathogen and application through spraying or dusting could be
disseminate it when the host is most susceptible done with usual application equipments.
to its effect. One approach to introduce and
colonize pathogens as permanent mortality factor 7) Permanent Control of Pest: On introduction
in the host population. This approach is called of pathogen in target pest population and them
the ‘Microbial Introduction’. its colonization brought about the permanent
measure of pest control through their self
Another microbial technique is to make dissemination within pest population.
the repeated applications of a pathogens as
microbial insecticide for the temporary 8) Ideally Suited for Integration with most
suppression of insect pests e.g. development of other Plant Protection Measures used in IPM
bacterium, Bacillus thuringiensis. This bacterium Programmes: Many pathogens are compactable
is produced by fermentation and is formulated as with chemical insecticides, fungicides, biological
a dust, wettable powder of emulsion. The agents and other methods of pest control like
material is applied like a chemical insecticide. Its plant resistance pheromones, chemosterilants etc.
effect is short lived and many applications are
needed. 9) Production Technology: Mass multiplication
of the pathogen could be done with simple
techniques which can be ideally suited for a
cottage type industry.
Advantages of Microbial Control
10) No fear of environmental pollution and
1) Host specificity: The relatively high degree of hence eco-friendly/environmental friendly
specificity of most pathogens tends to protect the measure as far as recent approach of man’s
beneficial insects. safety is concerned.

2) Ability of Multiply in their Target Hosts: Limitations or Disadvantages of Microbial

When microbial pathogens applied through Control
artificial dissemination for short term control of
the pest the disease will persist and spread in the 1) High Selectivity/Host Specificity: Since the
host population and initiate epizootics. They microbial agent is effective against only single
persist in the residual population and prevent pest species there is a very limited market
pest resurgence. The microbial agents the target potential.
pest at low levels for several years.
2) Requirement of Additional Control
3) No problem of Toxic Residues: Microbial Measures: An additional control measures are
agents are usually harmless and non-toxic to needed for non-target insect pest species. It
other forms of life because they do not possess present and not kept below ETL by natural
any toxic residues. The spray deposits on plant control factor.
surfaces are quickly inactivated by UV radiation
of sunlight. 3) The Correct Time of Application: In this
respect, the incubation period of disease, which
4) No Evidence of Resistance: Microbial do not is a critical factor and difficult to judge because
create resistance problems either in target or non of age specificity and stage specificity. The
target species. The absence of resistance to a pathogens attack on certain stage (larval) and do
microbial pathogen, make the insect pathogens not produce effect on eggs or adults.
as idea pesticidal agents for their use in pest Susceptibility of larvae also decreases with
management programmes. increase in age.

5) No Problem of Cross Resistance: The 4) Delayed Effect/Mortality: The pathogens

pathogens do not show cross resistance with require some time to produce response in their
chemical compounds. They can provide relief in
 26

target host owing to its long disease incubation 3. More than 100 species have been identified as
period. insect pathogens of the genus Bacillus are
identified as insect pathogens and they are of
5) The pathogens like viruses, bacteria must be commercial importance.
ingested as early as possible to produce effects,
while the fungi required entry through body 4. Bacillus species having bi-pesticidal
integument for which good coverage of spray potentially are classified under three groups as
deposits is important. under:

6) Storage Problem: It is necessary to maintain i) Obligate pathogens: Bacillus papillae

the pathogen in viable condition. Even average – milky disease causing organisms.
temperature and sunlight degrade the microbial
preparations. Exposure to sunlight causes UV ii) Crystalliferous spore
radiation and losses its virulent immediately. The former: Bacillus thuringiensis
pathogens have very short self life.
iii) Non crystalliferous facultative
7) Difficulty of Culturing in Large Quantities: pathogen: Bacillus cereus and B. sphaencus.
Rearing host insect on artificial diet is more
cumbersome and laborious works which requires 1) Milky diseases Bacillus papillae and
constant supervision. The whole organisms B. lentimorbus. Milky disease organisms are
techniques for in vivo prorogation of virus are able to infect only certain closely related beetles
fairly labourious and expensive. of the family Scarabacidae. About 62 species of
insects have been found to pick up infection by
8) Short Residual Effectiveness: This is the injection or soil inoculation. These bacteria
major limitation absent the effectiveness of multiply and speculated readily in the
pathogen under field conditions as sunlight haemolymph of the grubs. The turbidity due to
causes UV radiation. accumulating spores lead to milkiness of their
haemolymph and hence the “milky disease”.
9) Not legally protected and data needed for
registration is highly expensive. The discovery and practical application
of the milky disease bacteria for control of grubs
Bacterial Pathogens in Bio-controls of Crop of Japanese beetle in USA provided the first real
Pest encouragement for use of bacteria for insect
control. Preparations of B. popillae are resisted
1. These bacteria are present in the digestive tract and commercially marketed as ‘Doom’. The
of insects but seldom cause pathogenic infection spores are produced in vivo by inoculation of
because they lack the invasive power to penetrate grubs. B. popillae cause true septicemia in
through midgut wall. susceptible hosts. In nature, spores are ingested
and germinated in the insect get followed by
2. They are relatively harmless when remain in penetration these. Upon death of insect, the
midgut but pathogenic when introduced into disintegrating cadavers form a continuing
blood. inoculation in the soil. The necessity of
producing by the time consuming and
3. Their pathogenicity when introduced in blood uneconomical method of inoculating grubs limits
is due to temperature extremes, other pathogens the usefulness of these organisms at the present
and due to poor food quality. time.

4. Little efforts have been to use them as 2) Bacillus Thuringiensis (BT):-

microbial control agents for example, Serrstia
entomophile against grass grubs. 1. It is crystalline spore former: It
produces endospores and proteinaceous
Spore Forming Bacteria: parasporal crystal in sporulation time.

1. These bacteria are rod shaped, gram positive, 2. The cells produce crystal which
motile with many flagella. contains an endotoxin capable of pralysing the
gut of larvae. The toxic is known as “Delta
2. They form endospores in insect and promising endotoxin”.
organisms for microbial control.
 27

3. BT is widely distributed in nature and balance and lead to cellular swelling and lyses.
it can be isolated from various sources, viz., dead Intoxicated insect larvae quickly stop feeding
insects, litters of sericulture farm, soils, water, and eventually die. BT also produce other toxic
dusts etc. metabolites such as beta exotoxin, alpha
exotoxin and gamma exotoxin. These exotoxins
4 BT infests 525 species of insects from are more persistent and inhibit
stress from crowding etc. make the insect more reproduction in Spodoptera but have high
susceptible to the pathogen. mammalian toxicity and banned in USA by
EPA.
5. The UV light is harmful to spores and
crystals of BT Viruses in Bio-controls of Crop Pest

6. Generally susceptible insects are killed Viruses are a non cellular sub microscopic / ultra
by toxic crystals or a lethal septisemia. microscopic infective entily, less than 200 mu in
diameter and that multiples only as obligate
7. Recently genetic engineering has pathogen. Intra cellularly in host tissues and
helped to incorporating genes coding for Bt delta consist of a protein coat surrounding a core of
endotoxin into transgenic cowpea, cotton, self replicating nucleic acid either DNA/RNA.
tobacco and tomato plants so that internal
production of toxic crystals by such plants can
ward-off the attack of pests when visit for Viruses are the most exciting and promising
feeding. group of pathogenic micro-organisms under
consideration for use in biological insect pest
8. Local strain Bacillus thuringiensis ver. suppression. So far more than 1200 virus-host
Kenyae was isolated from meal moth, Ephastie relations have been described. Majority of them
cautella by BARC. Bombay which is effective are found in order Lepidoptera, (83%),
against potato tuber moth. Hymenoptera (10%), Diptera (4%) and few
examples from Coleoptera, Neuroptera, and
Orthoptera etc.

9. Bacillus thuringiensis var. israelensis

was isolated from south India and marketed The viruses are currently named and classified
under trade names as ’Doom’ Japidemic etc. on the basis of virus particle characteristics such
as shape, outline and symmetry, molecular
10. Bt is reported to be safe to honey bees weight of the nucleic acid as well as
and non-toxic to man. The reason for lack symptomology of the diseases, site of viral
of toxicity is mammals; the primary digestion of replication and sensitivity to chemicals. There
protein is at low PH. The stomach enzyme are six groups of viruses according to the criteria
pepsin, which has optimum pH value of 2, and classification approved by the International
degrades the endotoxin into a non toxic Committee on Taxonomy of viruses.
compound. But exotoxin produced by some of
strains of Bt has been found to be toxic to mice. a) Baculoviruses (BV): Main
characteristics of Baculoviruses are:
11. The product manufactured from
Bacillus thuringiensis var. kurstaki is marketed 1. Properties virus particle: Nucleic acid is a
trade names viz. Delfin, Dipel, Halt, Thuricide single molecule of circular super coiled DNA,
etc. protein virus particle (virion) structurally
complex and contain 10-25 polypeptides of
12. Twenty seven Bt biotypes/strains are which 4-11 are associated with necleocapsides,
known according to structure/sequence of several and carbohydrate present.
genes and gene products.
2. Replication is in host cell nuclei.
13. When ingested crystalline inclusion
initially dissolve in the midgut releasing one 3. Transmission naturally through food
or more proteins. These crystal proteins are contamination and experimentally by injection,
activated by digestive gut enzymes with infection or translocation cell cultures.
correct pH into toxic polypeptides. Smaller
activated toxins bind to cell membrane liming 1) Nuclear polyhedrosis virus (NPVs): These
the gut generating pores that disturb osmatic are the best known and account for 41% of the
 28

described arthropod viruses. They show great types of IBs may be produced along ovoid to
promises for practical use in pest suppression. irregular shaped IB, 2-8 um long and smaller
These viruses develop in the host cell nuclei and spindle shaped bodies, deveoid of
their virions are occluded singly or in groups in occluded virus particles. Because of their close
polyhedral inclusion bodies. The rod shaped relationship to vertebrate pox viruses
virion contains double stranded DNA and are conformity for safety of EPV before use.
230-420 nm long. The POBs are 0.2-15 um in
diameter. Virulent obligate pathogen requires d) No Occluded indescent Viruses (IV):
living cells for development and multiplicate. There are intensively studied by Smith
The NPV infect all insects cells regardless of (1967). The initial site of virus
their derivation and cause death. Polyhedral multiplication is in cytoplasm of host fat body’s
protein protects virion from action of chemical, cells. The viruses crystalise
drying, sunlight, enzymes and high temperature. spontaneously within the living insect o give it a
Free virus particle is less stable. It is highly host characteristic Iridescence by Bragg
specific with no effect on beneficial fauna. It is reflection. The Tipula iridensect virus (TIV) is
safe to plant birds and higher animals and man. It 130 nm in diameter and has icosahera shape. It
enters through injection of plant material into contains double stranded DNA and has
insect gut through mouth and cuticle. Infected been artificially transmitted successfully across
insect appear dull in colour and inceptive. ordinal lines to non- dipteous hosts in the
Feeding rate of insect is reduced. In advanced Lepidoptera and Coleoptera.
stage integument fragile and rapture on slight
disturbance emitting liquefied content (whitish General considerations for field application of
fluid). Incubation period is 4-5 in 20 days. BVs:
Earlier instars are more susceptible than 5th of
6th instar. Infected larvae hang invertedly from 1. Method of application: Foliar spray.
twigs.
2. Stage of pest: Early in stars are highly susceptible.
2) Granulosis viruses (GVs): It has also show
considerable promise as agents for insect pest 3. Dose of virus preparations : HNPV-250LE/ha
suppression. They develop in either the nucleus (1LE=6× PIB),2 to 3 sprays in early stages of
or cytoplasm of host fat, tracheal matrix or pest.
epithelial cells. The virions are occluded singly
in small inclusion bodies called capsules. The 4. Preparation of spray fluid: NPV in required
rod shaped virion contains DNA and are similar strength is mixed with good quality soft water
to NPV viruses. They usually oval occlusion +0.1% teepol or Trition-x-100.
bodies about 200×400 nm size. They enter
through ingestion. The diseased larvae are less 5. Time of application: Preferably in evening hours.
active, flaccid and fragile and period from
infection to death is 6 to 20 days.
6. Frequency of application: 2-4 application in
b) Cytoplasm polyhedrosis Virus case of NPV/weekly.
(CPV): It is also a promising group for
practical use. They develop only in the 7. Application equipment: High volume
cytoplasm of host midgut epithelial cells. The applications are more effective than low volume.
spherical virions are occluded singly in
polyhedral inclusion bodies and contain 8. Integration of chemicals: NPV is compatible
double stranded RNA. Their average diameter is with most of pesticides.
60 nm. The POBs ranges from 0.5-15 um in
diameter. Infection by CPVs is not always lethal 9. Use of adjuvants: Skimmed milk, juggary,
but shows larval growth reduces. Teepol, sandovit.

c) Entomopox viruses (EPV): This is a Fungi in Bio-controls of Crop Pest

recently discovered group. On the basis of
particle size and structure, there are apparently 3 Entomopathogenic fungi played an
EPV sub groups, each affecting different important role in the early development of Insect
insect orders. EPV replicate in the cytoplasm of Pathology and subsequently they were
host fat body cells and possible in heamocytes. considered as beneficial organisms with potential
Virions are ovoid cuboids, 200×300×200 nm as pest suppressive agents.
and contain double stranded DNA. Two
 29

Pathogenic fungal infections are referred Appressoria have been found in some fungi.
to as mycoses. Insect mycoses are cause by fungi There are the swelling produced at the end of
in the following classes: short germ tubes which attach to the cuticle and
send infection pegs into the host. They are
i) Phycomycetes: Entomophthora considered to provide firm attachment that the
fungus needs to physically force its way into the
ii) Ascomycetes: Cordycepes, Nectria host.

iii) Basidomycetes: Septobasidium Toxins: The former may have potential as

insecticides white the later are useful in
iv) Fungi imperfecti : Cephelosporium, elucidating the modes of action pathogens. The
Metarahizium, Penicillium, Verticlillum. normal site for toxin production is the
haemolymph. Materials to do on injection are
The Phycomycetes and Deuteromycetes produced in vitro by several insect pathogens.
contain the orders, families and genera which are Two such materials of known chemical
most commonly considered for species of composition from entomogenous fungi are:
entomogenous fungi in some 35 genera, very few
have been studied in details. The members of the (1) Destrusins A and B from
genera Beauverina (white muscardine) against Metarrhizium anisopliae and
Lepidoptera, Metarahizium (green muscardine)
against cockchafer beetle, and Entomophthora (2) Beanvericin from Beauveria basslana.
against aphids, jassids, housefly etc. and
Coelomomyces and Aspergillus have received Under field condition the disease development is
most of the infection. The taxonomy of mainly influenced by various aspects of three
entomogenous fungi is not static. main agents pathogen, host and environment
which interact and change at same time. Besides
The infective unit in most fungi is a temperature and humidity as major factors are
spore-usually a conidium. Invasion through the microclimate, light, air currents, host population
respiratory or alimentary tract has been reported. density, stress, host activity antagonisms or
Conidia usually germinate on the cuticle and synergism of other pathogens and genetic
then penetrate. Enzymes and mechanical forces makeup of disease. The pathogen is mainly
are involved. In most cases yeast like filaments influenced by its
of mycelium called hyphal bodies are produced
which usually float free and apparently multiply a) Dispersal
in the haemocoel. Some strains produce b) Viability
sufficient toxins in this stage to cause death. c) Inoculums size and
After death or even before in those strains which d) Virulence. Spores are widely
are weak toxin producers, normal thread like disseminated by wind and splashing of rain.
mycelium remifies throughout the internal Sunlight and humidity may kill spores. As far as
organs. This continues until insect is virtually host insect is concerned, the host population
filled with fungus. Condidiophores are then density and susceptibility to fungi govern the
produced which erupt through the cuticle and disease development.
produce spores on the outside of the insect.
In Deuteromycetes the conidiophores and The most successful examples are with
conidia are not produced unless the dead insect is Beavaria bassiana, Metarrhiziur anisopliae and
in a moist environment. few species of Entomophthora. The
entomogenous fungi can be used 3 different
Spore Germination: There is a great influence ways for insect control.
of environment condition on germination of
spores. The epicuticle is of special significance 1) Colonization: The fungus is
in disease induction since it is bere the fungal introduced into as insect population where it
spore must geminate before it can reach the becomes permanently established. Pest insects
underlying haemocoel and vital organs. At are killed year after year from one or few
germination one or more germ tubes (short introduction.
hypae) are produced from each spore.
2) Microbial Insecticides: Applications
Penetration of Cuticle: Germ tubes may grow are made repeatedly as required to control pest
on the surface of the insect for short distances or population like insecticides.
may begin to penetrate the cuticle immediately.
 30

3) Integrated Control: Control Nematodes in Bio-controls of Crop Pest

techniques are selected which have minimum
adverse effects on natural mortality factors like Nematodes are generally fusiform and
parasites, predators and pathogens. vermiform shape with a terminal mouth situation
on a rounded head and a tail tapered to pointed
Protozoa in Bio-controls of Crop Pest tip. They are invertebrates. Un-segmented and
multi cellular organisms which exhibit bilateral
The protozoa subphrla Sporozoa and symmetry and bisexuality.
onidospora contains numerous entomophilic
protozoans and most promising examples in It is the common fact that insect
biological insect pest suppression programmes. associated nematodes were included as microbial
The effects of protozoan infections are chronic pathogens for pest population suppression. The
rather than acute and they may affect their hosts nematodes species in the Mermithidae,
over a fairly long time period. Because of this, Neotylenchidae and Sterinerema are important.
disease is often manifested in the host insect only Poinar (1975) recorded 27 families of
by a reduction vitality, fecundity and life span. entomogenous nematodes associated with 19
insect orders. Most of the nematodes that cause
The naturally occurring epizootics of injury to their insect hosts are endo-parasitic,
protozoan disease in insect pest like European occurring in the haemocoel, gut lumen,
corn borer, some Lepidoptera, several species of malpighian tubules, ovaries or other organs.
flies, aquatic Diptera including mosquitoes and Infection may be either passive such as when
grasshoppers. The Neogregarires occurs eggs of infective juveniles are accidentally eaten
primarily in the fat body and intestinal tract of by susceptible hosts or active when the infective
Coleoptera, Lepidoptera, Hemiptera and Diptera. juveniles penetrate their host somatic cuticles.
Mettasia grandis is an important pathogen of the Nematode activity, in the host may result in sub-
cotton boll weevil and showed considerable lethal injury cause by nutritional depletion or
promise. organ disturbance. It may be expressed as
retarded growth, reduced activity, lower
The infective spores are totally empty. fecundity, eventually sterility and even the
The emerging sporozoites and motile in the gut production of inter sexes. On the other hand
tract and soon penetrate the gut to the haemocoel death generally from the mechanical destruction
and infect cells of susceptible tissues within 2 of host tissue.
days. The diseased larvae die early within a week
and shrivel so badly that they are used for spore Poinar (1971) used a DD-136 strain of
production, Nosema locustae also attacks Neoaplectana carpoceapsae Weise against 12
grasshopper or locust species and spores and insect pests which included from the orders of
applied in bran bait. Lepidoptera Coleoptera and Diptera. The
bacterium associated with these nematode names
Rickettsiae in Bio-controls of Crop Pest as Achromobacter nematophilus Poinar and
Thoma. The infective juveniles of DD-136 are
Rickettsiae have comparable size of 0.2×0.3 to normally ingested by their insect host and once
3.0 um and obligate intracellular development in the gut lumen they pass through the
and their susceptibility to antibiotics indicates alimentary wall into the haemocoel. There the
similarity to bacterial cell walls and contains bacteria are released through the anus which
both RNA and DNA in ratio of 3:1. The causes a septicemic death to the host in 24-48
Rickettsiae develop and multiply on the cell hrs. The nematodes feed on the multiplying
cytoplasm where they fill the vacuolar areas. In bacteria and the dead host tissues passing
ticks, they develop in cell nuclei, the two genera through several generations in which their
of this group are important. numbers increase tremendously.

1) Enterella: The Enterella spp. grows The ensheathed juveniles eventually

only intra-cellularly in the gut epithelium produced along with their associated specific
of the host and destroys it. bacteria, leave the dead depleted host and if they
encounter a suitable new host the process is
2) Rickettsiella: These species primarily repeated. The complete life cycle takes 5-8 days
attack the fat body and blood cells but and in a single were moth larvae (Gelleria
may also cause generalized mellonella) more than 1,00,000 juveniles may be
infection. Rickettsiella popillae cause infection produced. House et. al. (1965) devised new
by a greenish blue discolouration of fat rearing technique using dog food providing large
 31

number of nematodes at low cost. The field test Some Important Insect Parasitoids
with DD-136 provided variable results against
forest and agricultural pest. More than 60% 1. Trichogramma: Trichogramma spp. Are true
mortality against codling moth, tobacco egg parasitoids widely distributed in insect. The
budworm, Heliothis spp. was recorded. Moisture taxonomy of the various species is difficult, but
requirement in the microhabital of this it is now been classified that over 200 insects
nematodes is important factor to avoid species belonging to 70 families and 8 orders in
desiccation. They can be applied with wetting diverse habits are parasitized by species,
agents and the pathogens B. thuringiensis. subspecies and various strains of Trichogramma.
Out of 26 Trichogramma species recorded in
Mermithid nematodes parasites of India T. japonicum and T. achea are widely
mosquito ate worldwide in distribution. Because distributed and are key factors for many crops
of their obligate nature, most are difficult to mass pest in India. These parasitoids are mostly used
rear economically and hence have been seriously against pests like sugarcane borer (Chilo spp),
considered as agents for biological insect pest paddy stem borer, tomato fruit borer, cutworms,
until recent years. They have great potential as cotton bollworms etc.
they are generally well adopted to their host,
fairly host specific and kill their hosts upon A female lays about 1 to 20 eggs in one
emergence. They do not require addition food host egg depending on size of eggs but in the
once they have left their host to mature, mate and eggs of sugarcane bores only 1-2 eggs of
deposit their eggs. They have successfully used Trichogramma are posited per egg. Its fecuandity
in field tests. Current work on nematode is on varies from 20 to 200 eggs according to species
Steinernema spp. and Heterohabditis spp. reared and longevity of adults. Incubation period of
on Gelletia mellonella and used for control of eggs lasts for a day (16 to 24 hours). Larval
white grubs, cut worms and other soil inhabits period is 2-3 days, prepupal and pupal periods
insect pests. varies 2-3 days, and total life cycle is completed
in 8 – 10 days during summer and 9 – 12 days
Difference Between or Characteristics of during winter. Host eggs become dark in 3 -4
Parasite, Parasitoid and Predator days after the parasitilization because of
accumulation of urate granules unorganized eggs
remain 1:1 ( M: F ). Host searching capacity is
Sr. Properties Parasite Parasitoid Predator up to 3-5 meters in filed. Rice moth, coryra
No.
cephalonica is used as facitituous host for
multiplication of Trichogramma.
1 Size Smaller than host Same size as Large than host
host
2. Bracon brevicornis: It is a potent larval
2 Host Both larva and host Only larva Both larva and host parasitoids of coconut black headed caterpillar.
and adults The parasitoid is an external gregarious, larval
parasitoid and lays about 6 to 2 eggs pr host
3 No. of host One One More than one
larvae. Its egg stage lasts for 24 to 48 hrs larval
stage 5 – 6 day and pupal stage 4 to 6 days. A life
4 Injury to hostFeed without killing Paralyze to Kill to devour
oviposition cycle of the parasitoids is completed within 15
days. The pupae of the parasitoids are silvery
5 Activity Function at low host Function at Function at higher cocoons can be stored for 10 – 15 days in
density so efficient low host host density so refrigeration. In laboratory, the parasitoids are
density so efficient.
efficient reared on larvae of rice moth, Corcyra
cephalonica, and the adult parasitoids of Bracan
6 Diurnal or Diurnal/Nocturnal Diurnal Diurnal/Nocturnal brevicornis are used for releasing them in
Nocturnal
coconut plantation against target pests. Release
of 40,000 to 50,000 and per r hectares week and
7 Host Great Great Not so great
Specificity follow such 4- 6 releases are recommended in
fields.
8 Suitability Not suited Best suited Suited
for Some Important Insect Predators
biological
control
The first known use of the tactic of
9 Examples Mosquitoes, lice bed Parasitic Mantids, lady bird biological insect pest suppression was in China
bugs wasps tachinidbeetles
flies
around 300 A.D. wherein ants were used to
protect orange groves from developing wormy
 32

fruit. The red wood ants are considered

important in maintaining forest insect pest 4. Inter Relation of the Insect Agent and
population in balanced condition in 12th century. Food: Struggle for existence, Insect attacked
Their food consists of stages of Lepidopterous weed become weak and other species may
caterpillar. This is an example to be quoted for become dominant. Disturbance to plant feeders
efficient facultative predator mired, Cyrtorhinus by natural calamities.
modulus have been proved as an effective
predator the eggs of the sugarcane leaf hopper. 5. Risk of Introduction and Host Specificity:
Its first release was made in 1923 from Great fear of become weed feeder as feeder of
Australian stock and late from Fiji and by 1923 economic plants.
the sugarcane hopper was suppressed.
6. Specificity Tests, Starvation: Leaf beetle,
1) Vedalia Beetle, Rodolia Cardinalis allied to host or even more on cabbage but found
Mulsant: This is probably the most frequent not multiplied in field.
mentioned predator in classical biological control
literature. It has been thoroughly received by 7. Nature of Infection and Prospectus of
DeBack (1974). The successful story of the Success: Successful weed killer should have no
Vedalia beetle against cottony cushion scale, pest of economic plants, should attack vital plant
Icerya purchasi in California on citrus has parts, should have least natural enemies and
already been outlined C.V. Riley campaign. Like should have fast multiplication rate.
success in California, in has been a repeated 30-
50 country around the world where this beetle Examples of Biological Weed Control:
has been released. Adults of Vedalia beetle male
and have a preoviposition period of 4 weeks in 1. Weed Lantana camara controlled by
the summer and 1-3 weeks in the winter. The introduction of Telonemia scrupulosa in India
eggs are laid singly or in small cluster. (1944).

Biological Control of Weeds 2. Prickly pear, Opuntia spp. controlled by

introduction of cochineal insects, Dactylopius
Weed is a plant in the wrong place. On spp.
the other hand, weeds may be valuable plants in
other situations. This fact is fundamental to a 3. Water hyacinth controlled by weevils,
consideration of biological control. In fact the Neochetina bruchi and Neochetina eichhorniae
method of biological control of weed has been and hydrophilic mite, Orthogalumna terebrantis.
used when other methods found inadequate. To
reduce the densities to non economic levels by
either direct or indirect action of natural enemies
being used.

Fundamental of Biological Control of Weed: Steps in Establishing Biological Control

Programs
1. Concept of Natural Control as Related to
Weed: The competitive weed should be fast Following program may be followed for
growing e.g. Stylo. introduction for beneficial organism:

2. Kind of Natural Enemies: Species insect 1) Exact Identification of Pest: For

feeding made preferred roots, stems, seeds and identification of pest first recognize the
flowers. occurrence of damage. Then determine the
specific cause of damage and undertake precise
3. Nature of Controlling Action: Every weed taxonomic identification. The species names give
cannot be controlled biological with insect. access for availability of literature and explore
the possibilities of utilizing the natural enemy of
a. Injury: Direct feeding on vital parts related species.
like flowers, seeds or killing the plants. Indirect
feeding injury increase susceptibility to diseases 2) Origin, Geographic Distribution and
or secondary parasites. Ecological Requirements: Examine the degree
of damage of the pest in homeland indicating
b. Plant Parts Attacked: Vital plant part existence of natural enemy and their importation.
should be attacked before seed formation. Determine pests’ potential important
 33

information. If the species has been the subject minimum possible techniques to the
of successful programme earlier elsewhere, specific pest and its natural enemy.
employ similar procedure e.g. Vedalia beetle
used against cottony cushion scale in California. b. Hand collection of natural enemies of
If no work has been done on the target pest, then host is feasible method. But artificially dense
the techniques of other related natural enemy population of host is encouraged or created in
available from similar work may be followed. controlled area subject to exposure to the
desired parasitoid.
3) Host Parasitoid Lists and Other Faunal
Surveys: c. Collection site need not to be at
remote, exotic or inaccessible.
a. If target species is not an important pest in its
place of origin it may be a god reason that 7) Shipment of beneficial organisms:
density dependent natural enemy is present these
to regulate population size. a. Most critical step in introduction of
natural enemy programme is transportation from
b. If the species is pest its potentially useful origin to place of introduction.
natural enemy may have moved to new
environment free from hyperparasites. b. Necessity of providing food and water
to sustain life during journey sometimes need
c. Search literature for previous specific studies living host/prey insects on potted plants.
and its natural enemies. Refer
lists/catalogues/area-wise faunistic surveys for c. Permit for the agencies for importation
diseases, parasitoids and predators present. of organisms.

4) Field Study of both Target Insect and d. Shipment of material in a series of

Beneficial Organisms: small shipment rather than in a single large one.

a. From literature survey, find e. Containers should be strong enough to

information on location/native habitat, pest survive rough handling and prevent escape
status, ecology and its natural enemies. during shipment route.

b. Undertake field studies in native f. There are wooden containers or

habitat for collecting sufficient natural cardboard mailing tubes, aerated plastic
enemies for shipment and locate most containers, Vacuum flasks or foam insulated
suitable area for collection of natural enemies in containers with suitable labels for cautions of
large quantity. temperature extremes or adverse condition.

g. Shipment during development stages

becomes easier.
5) Prediction of Success and Efficacy:
h. As a part of each shipment, attack
a. Collection preliminary information on information sheet indicating, identity source,
ecology compatibility and effect of natural number of natural enemies and dates of
enemy on pest density, its behavior collection of shipment.
synchronization biotypes etc.
8) Quarantine:
b. Predict certainty in the outcome of
Biological insect pest suppression before. It is a. The purpose of quarantine is twofold.
carries out. Success in introducing natural enemy The procedure prevents the premature escape of
which has proven itself before against the the imported insects, and it prevents the
same target pest in a similar environment contamination of entomophage culture by native
elsewhere. species.

6) Collection of Beneficial Organisms: b. Adequate screening of the shipment

before release to eliminate hyper parasitoids.
a. Collection of natural enemies for It may be done by rearing the imported species
importation in short possible time. Employ for one or more generations under controlled
conditions.
 34

c. Admittance is usually restricted k. Release larger colonies at few point,

authorized personnel only. multiple induction quickly regulate pest
spectrum.
9) Propagation:

a. Introduce large number of natural 11) Follow-up Recoveries:

enemies.
a. Determination of establishment of
b. Synchronies entomophage and pest life introduced natural enemy and its rate of
cycles with carefully timed propagative output, dispersal.
rearing of natural enemy all year round and
storing the progeny until release. b. Carry out making field observation and
collection in and near the sites of release or
c. Complete knowledge of life cycle, by visual determination in the field after the sites
biology and behaviors, proper rearing condition or release or by visual determination in the field
and a suitable laboratory host may be factitious after one generation or dissect parasitized host or
(unnatural) host or artificial diet. by rearing of adults from field collected host
material.
10) Release and colonization:
c. Recoveries:The first instance of
a. A current trend toward the earliest recovery indicate temporary or initial
possible attempt is field release. establishment of natural enemy. The second or
third instance indicate permanent establishment
b. Extensive laboratory propagation only if it is recovered in three successive year
minimal colonization efforts. after its release.

c. Incomplete understanding of the host- 12) Evaluation:

parasitoid or prey-predator relationship may lead
to poor adaptation of natural enemy. Assessment of effectiveness of natural enemy by
careful and continuous monitoring of increase
d. Alternate host, required food supplies and spread of introduced entomophages.
of nectar or polled for the adults may be missing
for the introduced natural enemy which eater It involves 3 ways.
establishment of entomophage.
a. Qualitative analysis: By frequent
e. Proper time of introduction of natural extensive sampling observation of the progress
enemy against target pest of univoltine type. and spread of introduced species and apparent
cause effect relationship to decline pest
f. Predators should be released with populations.
greatest assurance of mate
g. Select promising site for introduction b. Experimental exclusion procedure:
based on preceding information for easy and By comparing the population density of the pest
natural spread. in the absence of newly introduced natural
enemy with that in presence of the introduced
h. Colonization by installation of field natural enemy with that in the presence of the
cages i.e. for predators to minimize initial spread introduced species
/ dispersal and protect against native competitor
species. c. Quantitative mathematical analysis:
It is best proof of success or failure. it involves
i. Predict weather conditions like frosts, development of extensive life tables of pest both
heat waves, heavy rains / winds, bright sunshine before and after the introduction of natural
which causes high mortality of colonized natural enemy.
enemy.
Future Needs of Biological Pest Suppression
j. Release are best made in early
mornings or late evening when light levels are In future, Non Government Organizations
subdued, temperatures are lower and humidity is (NGOs) should to expedite the pilot projects on
high. mass production of same biotic agents like
Trichogramma which have great potential to
 35

control pest like sugarcane borers, maize, increase the effectiveness against the less
sorghum, paddy cotton bollworms moths etc. susceptible species.
predators such as Chrysopid and Coccinellids for
aphids, mealy bugs on cotton, tobacco, grape
guava and citrus guava and citrus similarly
pathogens like NPV and saprophytic fungi and
produce toxins (Gliotoxin and Varadin) which
will the rute root disease of pulses and oilseeds.

Government may also consider the

following suggestions for future works which
may helps farmers in adopting bio control
technology:

1. Popularization of literature through local

languages.

2. Increasing finance to other bio control projects

beside AICRPBC sanctioned by ICAR, New
Delhi, and Department of Science and
Technology and DBT, Government of India.

3. Judicious as well as restricted import of biotic

agents from other countries.

4. Emphasis on exploration of indigenous biotic

agents.

5. Preparation of ‘Field guide for biotic agents’

along with their visible stages and natural hosts.

6. Establishment of commercial factories to

ensure supply of potential biotic agents.

7. Establishment of National Institute on

Conservation of Biotic Agents along with
network at district level.

8. Studies on biotic agents in relation to

intercropping, cultural practices and other forms
of organic farming.

Current problems with the use of chemical

insecticides and emphasis on low impact
sustainable agricultural have pushed the
microbial agents to the fore front for use in pest
management. However, microbial pesticide has
not been economically competitive with
chemical insecticides, primarily due to their host
specificity. The relatively slow speed with which
microorganism kill their hosts has hampered
their effectiveness as well as acceptance by
potential users. A wide range of environmental
factors affects the efficacy of microbial
pesticides. Development of resistance to viruses
and Bt is a matter of serious concern. However,
the use of both naturally occurring and
genetically engineered microorganisms may