American-Eurasian J. Agric. & Environ. Sci.

, 13 (5): 673-676, 2013

ISSN 1818-6769
© IDOSI Publications, 2013
DOI: 10.5829/idosi.aejaes.2013.13.05.1928

Evaluation of Some Plant Products for the Control of the

Cowpea Weevil (Callosobruchus maculatus)

D.M. Jibrin, J. Abdullah and U. Ibrahim

College of Agriculture, Division of Agricultural Colleges,

Ahmadu Bello University, Zaria, Nigeria

Abstract: A laboratory experiment was conducted for fourteen weeks to determine the efficacy of some selected
plant product extracts (Azadiracta indica seeds, Aloe vera, flame seeds and Trema orientalis) for the control of
cowpea weevil (Callosobruchus. maculatus). The treatments consisted of a local variety of cowpea (kanannado)
and four plants extracts (Trema orientalis, Aloe vera gel, flame tree seeds powder, Neem oil and the control.
The treatments were laid out in a completely randomized design, replicated four times. Data were collected on
Mortality rate, moisture content, Weight loss and Germination percentage. Data obtained were subjected to
analysis of variance and treatment means separated using the LSD differences between means were compared
at the five percent level of significance. Neem plant extract was used as standard to check the performance of
the other plant extracts. The results revealed that by the first few weeks Neem oil being of proven potency
showed initial superior performances as compared to the other plant extracts. At the end of the experiment the
control treatment and flame tree seeds showed the same degree of control, neem was significantly different from
the other treatment while Aloe vera and the control showed the same degree of control.

Key words: Cowpea Different plant extracts C. maculatus

INTRODUCTION resistance, pest resurgence as well as environmental

degradation [6] resulting in world-wide call to minimize
Like other crops, cowpea is attacked by a wide range their usage and to develop less hazardous pest control
of diseases and pests [1]. Almost all parts of the crops are measures [7]. The persistence nature of most of the
susceptible to insect infestation and more than Eighty five chemical insecticide on our environment, coupled with
insect species have been found to cause damage to high cost and unavailability at critical periods of
cowpea [2]. Callosobruchus maculatus is reported as requirement, high level of toxicity which bring about
the most important bruchid that attacks cowpea if deleterious effect on human being, animals and the
unchecked, C. maculatus is a field to storage pest. The general environment necessitate the investigate of
infestation which starts in the field causes damage alternative formulation and dosage rate of some plant
that ranges from rendering cowpea unsuitable for (Neem, Aloe vera, flame tree seeds and Trema orientalis)
consumption to reduced viability and as populations as insecticides required for optimum storage of cowpea.
builds up, great losses can be recorded [3]. The seeds The central challenge to increasing cowpea yield is most
lose 30% of their weight [4]. In Nigeria, cowpea losses probably insect pest infestation aside other factors such
by beetles have been estimated at 2.44 million tonnes as lack of capital, poor production technology, poor
for 1981/82 and 3.67 million tonnes in 1984/85 [5]. marketing and inadequate extension services. Fortunately,
In the past control measures adopted by various nature has offered us a profusion of plants for use in crop
governments and research institutes were concentrated protection. These plant materials have been used by small
on storage structures such as barns, granaries (Rumbus) holder farmers in Nigeria to protect stored product from
and silos. Thereafter, insecticides were introduced but insect pest damage for a long time. Although, some of
these sooner than later created such problems as pest these plant species (Neem, Aloe vera, Flame tree seeds

Corresponding Author: U. Ibrahim, College of Agriculture, Division of Agricultural Colleges,

Ahmadu Bello University, Zaria, Nigeria, Tel: +2348034374967.
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and Trema orientalis) many have given some measure of experiment was set up in a completely randomized design
control against C. maculatus based on individual material and there were four replications. 1.00g, 2.00g and 3.00g of
used, yet, no attempt has so far been made to specifically the plant products (powders of flame tree seeds, Trema
screen and coordinate their efficacies in a single orientalis and Aloe vera gel)1.00m,2.00m and 3.00m of
experiment. Neem oil constituted the treatment, except for the control
The objective of this study is to evaluate the experiment that was untreated. The 48 treatments were
comparative efficacy of plant products and to determine labeled, covered and kept under room temperature in the
which has the best bioactivity against C. maculatus on laboratory for 14 weeks on a table top.
stored cowpea and to ascertain appropriate levels of plant
product required for effective control of the beetle on Data were collected on the following parameters:
stored cowpea. Problems in the tropics appear to be
greater than are obtained in the temperate climate Mortality rate
presumably because of optimal conditions of temperature Moisture content.
and humidity for pest development found in the former Weight loss
[7]. In Nigeria, C. maculatus is a major primary pest of Germination percentage
stored cowpea grains although infestation begins in the
field and is carried over into the store where it becomes However, the variable/ parameters were derived base
the predominant pest problem [8]. on the above criteria.
After one week, each treatment was observed for
MATERIALS AND METHODS mortality by counting the number of dead and active
C. maculatus and recorded.
The experiment was carried out in the laboratory at
Samaru College of Agriculture, Division of Agricultural Using the formula Mortality rate =
Number of dead C. maculatus
Total number of C. maculatus
Colleges, Ahmadu Bello University Samaru Zaria-Kaduna
Nigeria (11° 11’N,07° 38’686 m above sea level). The
experimental materials used for this research were Data collected were subjected to analysis of variance
obtained from Samaru market and the materials include a and treatment means separated using LSD.
local variety of cowpea (Kanannado). Trema orientalis The moisture content of the cowpea was determined
(Pigeon wood), Aloe vera, Flame tree seeds and the neem using electric oven dryer at department of soil science
oil was obtained from NARICT Zaria were used as the laboratory/ABU, Zaria. The randomly selected samples
treatments. The cowpea seeds used in this experiment were placed on petrict dishes and placed into the oven for
were sterilized / fumigated with ½ tablets of Aluminum four hours to dry. The dried sample was removed from the
phosphates in air tight containers for 72 hours to kill any oven at 100 °C and the container was covered to avoid
residual infestation or eggs on the grains. The fumigated reabsorbtion of moisture from the environment,
pulses were spread on a sack at room temperature in the furthermore, the sample was allowed to cool down for
laboratory for 48 hours to neutralize the effect of force about 2 hour before the reading was taken. The formula
toxin on the seed, for subsequent use in the trails. below was used in determining the moisture content of
In constituting the treatment dry flame tree seeds and the sample.
Trema orientalis (whole plant) were ground to powder
and sieved. And the Aloe vera gel was extracted from Initial weight of dish + Sample-final
Aloe vera plant. weight of dish + Sample
%Moisture Content = X 100
Initial weight of sample + dish-Weight of dish
The Bruchid, C.maculatus, stocks which are of
uniform size and age (between 0-24 hours old) were At the end of the experiment that is the 14th week each
collected from infested cowpea at cowpea production unit treatment was weighted to assess the final weight loss
IAR ABU Zaria. The Bruchids were reared in a kilner jar due to feeding of the insect and the data collected were
for four [8] weeks for new generation and population build used to find the percentage weight loss.
up. Fourty eight (48) Glass jars were used to conduct this
trial. Each glass jar contained 200 grames of clean cowpea Initial weight-Final weight
% weight loss = x100
and five [9] pairs of newly emerged adult bruchids. The Initial weight

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At the end of the 14th week of the experiment the Table 3: Germination Percentage of Cowpea at 14 Weeks after Treatment

grains were tested for viability and germination. 20 seeds Plant Extracts Planted Germinated Germination Percentage
were randomly picked from each jar for all the treatment NEEM OIL 20 0 0
and placed in a Petri dishes lined with moistened filter FLAME SEEDS 20 0 0
paper. These were left on the laboratory bench at a ALOE VERA 20 0 0
temperature of 27°C for 7 days after which germination TREMA 20 0 0
percentage was calculated. CONTROL 20 0 0
Means with the same letters in the column are not significantly different at
Number of germinated seed X100 0.05 level of significance
Using the formula % Germination = -----------------------------------------------
Total number of seed planted

RESULTS

Mortality rate was decreasing as the weeks after

application of treatments increase. At 14th week the
mortality was highest for neem followed by aleovera,
trema, flame seed. The control had the lowest mortality
rate. As shown in figure 1.
At the end of 14th week cowpea treated with Neem oil
was the only one that lost moisture while those treated Fig. 1: Mortality rate of C. maculatus (%) at different
with Flame gain 3.25%, Aloe vera 1%, Trema 0.5% and the week under different control strategies
control 3.25%.This shows a significantly higher
performance of neem over the other treatments at 5% level At 14th week, cowpea treated with neem has the
of significance (Table 2). lowest weight lost (2.5%) as compared to other treatments
followed by that treated with Aloe vera (32.5%), which
Table 1: Moisture Content of Cowpea Samples Treated with Plant was significantly lower to other treatments; Flame powder
Extracts at the Beginning and at 14 Weeks after Treatment (60 %), trema (6.52%) and the control (70%) as shown in
% of Moisture Content Tables 2 and 3.There was no significant difference
---------------------------- Moisture between cowpea treated with Flame powderd, Trema Aloe
Plant Extracts Initial Final Gain or Loss vera and the control This clearly indicates that Neem oil
Neem Oil 2.0 1.0 1a
offer better protection of cowpea against feeding and
FLAME SEEDS 1.75 5 -3.25b
development of the bruchid. There was no significant
difference among the treatment in term of germination
ALOE VERA 2.5 3.5 -1 b
percentage (Table 3) at the 14th week. None of the seeds
TREMA 2 2.5 -0.5 b
germinated.
CONTROL 2 3.5 -1.5 b
Means with the same letters in the column are not significantly different at
DISCUSSION
0.05 level of significance

All the treatments gave varying degree of control

Table 2: Weight Loss of Cowpea at 14 Weeks after Treatment
over a short period but soon worn out including Neem
Weight Loss Change in Weight which is of proven efficacy. The use of Zanthoxylum
-------------------------- ------------------------ xanthoxyloids bark and root was found to increase high
Plant Extracts Initial Final % G mortality rate of insect as reported by [9]. [3] also found
NEEM OIL 200 195 5 2.5a that Oleoresin was very effective against legume flower
FLAME SEEDS 200 80 120 60c bud thrips and that the toxicity was both time and dose
ALOE VERA 200 135 65 32.5b dependent. [9] found garlic to be effective in the control
TREMA 200 75 125 62.5c of maize weevil. [4] also found the use of aqueous extract
CONTROL 200 60 140 70c of neem to be effective against cowpea defoliator. All
Means with the same letters in the column are not significantly different at these shows that various plant extracts are effective
0.05 level of significance against insects in different crops

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