MANAGEMENT OF STORAGE PESTS

Dr. Mariadoss A, Asst. Director (RPM/Ent)

Introduction

Grains under storage are damaged by storage pests such as insects, rodents, fungi and birds
which cause both quantitative and qualitative losses in oilseeds.

Storage insect pests are classified in to two groups: 1. Major / Primary pests 2. Minor /
secondary pests

Major pests: These pests can break the kernal and make them powder. They can cause huge
damage and storage loss. They also contaminate the grains.

Minor pests: These pests cannot break the kernal. They feed on broken kernals and milled
products. They contaminate the oil seeds and milled products.

During storage of grains and other agricultural commodities, considerable quantitative and
qualitative losses are caused by the storage insect pests. At high moisture, their growth and
multiplication is very fast. The optimum conditions of temperature and relative humidity for
the rapid growth and multiplication of storage insect pests range from 25 to 35 oC and 60 to
65% respectively.

Management of Storage pests

1. Prophylactic measures:
"Prevention is better than cure". Hence the following preventive measures can be undertaken
at storage places in order reduce the pest incidence

i. Proper inspection and analysis of stocks received before acceptance

ii. Hygiene or sanitation inside and outside the godowns
iii. Aeration of godowns
iv. Prophylactic spraying with insecticides

1.1. Proper inspection and analysis of stocks received before acceptance for storage

When the stocks are received at storage point or whichever the oilseeds that are going to be
stored have to be thoroughly inspected before start storage of those commodities.
Representative sample has to be taken and it has to be analysed for moisture content and
presence of insects. The commodities beyond safe storage moisture content will deteriorate
quickly and prone to insect and mould attacks. Before accepting the food grain stocks, the
godowns shall be inspected to check hygiene, cleanliness, storage worthiness and the godown
is pest free.

Sampling Random samples shall be drawn from the food grain bags with the
help of parkhi on all sides of the lot received through wagon/truck
Visual Inspection Visual Inspection shall be done at the time of receipt of food grains
to ascertain the following points
i) Food grains shall be inspected for identifying damage,
infestation, slack bags and cut & torn bags.
ii) Unsound bags shall be segregated and kept separately, duly
identified and recorded.
Inspection process i) For food grains further inspection shall be carried out by
testing the grains moisture followed by analysis,
classification, categorization / grading. The maximum
moisture percentage for safe storage of rice and paddy is be
14% and for wheat is 12%.
ii) If the food grains are found within the prescribed quality
specifications the same shall be accepted for storage.
iii) In case of storage of FCI stocks, receipt of food grains with
quality complaint shall be informed to the depositor or
consignor in writing within 72 hours detailing the complete
quality issue
iv) The infested stocks shall be fumigated within 48 hrs hours
to avoid cross infestation to pest free stocks

1.2. Hygiene or sanitation inside and outside the godowns

1.2.1. Sanitation inside the godowns

• Necessary repairs like arresting roof and cable wall leakage, replacement of damaged
sheets, securing windows and ventilators with wire mesh shall be done to make the
godowns storage worthy.
• Before storage of commodities inside the godown ensure that the godown is well
cleaned. Godowns shall be cleaned thoroughly to avoid any residual infestation
 • Empty godown shall be kept clean & tidy free from any harbouring insects, cobwebs,
spiders and other pests
• Floor sweeping has to be done on regular basis and spillages has to be collected on
day-to-day basis, cleaned and bagged to mother stack.
• Wall cleaning has to be done. No cracks and crevices should be there in wall to avoid
harboring of pests.
• Cob webs removal has to be done regularly to improve the hygiene condition inside
the godown
• Disposal of waste / damaged grains has to be done timely to avoid further
deterioration and pest multiplication.
• Sacks / gunnies used shall be sound enough. The cut and torn portions has to be
stitched and closed.
• Ventilators & windows secured with wire mesh to prevent the escape of insects
during prophylactic spraying with insecticides
• Roof leakages and cable wall leakages have to be arrested immediately to avoid entry
of rain water. The rain water can soak the grains leading to sprouting or decrease in
bulk density of grains makes it unsuitable for storage.
• Proper Stacking is very much required to take up spraying and fumigation operations
inside the godown.
• Sufficient gap should be given from the walls, stack to stack, Passage etc.
• Material should not be stored on the floor
• Proper Dunnage - timber pallets/Poly pallets/ or Bamboo mats or black polythene
sheets can be used.
• Goods of different classes or grades or quality have to be stored separately and
arranged in such a way that stock taking and verification becomes easy and effective.

1.2.2. Sanitation outside the godowns

• Clean platform – The platforms where loading and unloading operations happens has
to be clean without any spillages. If there are spillages will attract storage insects and
rodents and will result in damage of grains and pest multiplication.
• No steps should be kept in the platform for having entry to godowns. Keeping the
steps will make the platform not rodent free. The rodents will have easy access and
movement into the godowns.
 • Clean roads – Keeping the roads inside the warehouse premises is an important
measure to avoid harborage of pests and also for easy movement of trucks.
• Dumping wastes – No waste has to be thrown here and there in the warehouse
premises. The wastes and damaged grains have to be disposed of safely by following
laid down procedures.
• Vegetation free – The warehouse premises should not be occupied by green
vegetation. Vegetative growth should be removed at periodical intervals to keep the
depot premises free from insect breeding, reptiles, bird nests, rat burrows and to
ensure overall hygienic condition. One can do away the control of vegetation by spray
of Glyphosate SL.
• The vegetation like small trees that are growing on the top roof and side wall of
godowns / building shall be periodically removed to avoid damage to the structures.
• No spillage should be on roads and platforms to avoid attraction of insects and
rodents.
• Proper drainage system should be in place to avoid flooding of godowns and damage
of stocks during rainy season.

1.3. Aeration:
Aeration is a process of passing air through stored grain at low flow rates. This can be
achieved by keep opening the windows and ventillators and also all doors / shutters open
during the day time. Aeration helps in excess moisture removal, temperature reduction
inside the godowns, for quality maintenance in the commodities and highly useful when
moisture content is high.

1.3.1. Objectives of aeration:

• Removal of generated heat and moisture inside the godown
• Maintenance of uniform condition inside the godown
• Removing/ reducing odour from grains which have higher moisture
• Removing dry heat generated by respiration of insects and grains
• Reduce moisture accumulation
• Helps in fumigant application
1.3.2. Aeration inside the warehouse / godowns
• Doors installed opposite to alleyways each other and has to be opened daily to ensure
movement of air inside the godown
• 6% of wall space for ventilators should be provided while constructing the godowns
for proper ventillation
• Doors shall be kept open during day
• Movement of natural air shall be ensured

1.3.3. Benefits of Aeration

• Reduces insect pest population in the godowns with food grains
• Grain quality is preserved
• There will be moisture reduction
• Temperature reduction can be realized
• Reduces the mould attack in food grains
• Colour and aroma can be maintained in spices by proper aeration.

1.4. Prophylactic spraying with insecticides

• Immediately on receipt of stocks spraying with malathion 50% EC can be done
• Prophylactic spraying can be repeated once in two weeks
• Air-charging inside the warehouse is done with DDVP 76% EC. However the
insecticide DDVP will not be in Indian markets after 31st Dec 2020 as it will be
banned.
• Prophylactic spraying helps to control flying / crawling insects
• Generally prophylactic spraying is done during the later part of the day prefereably
evening and in the week ends for more efficacy
• Before spraying godown should be cleaned and spillage collected and covered to
avoid contamination by insecticides.

1.4.1. Effect of spraying sub lethal doses:

Sufficient care has to be taken to go with correct and required dosage of chemical while
undertaking prophylactic spraying. Undertaking spraying operation with sub lethal dosage of
insecticides is always harmful and results in
• Development of resistance to insecticides in insects
• Sudden increase in insect population
 • Difficult to control the insects that got resistance
• Damages the commodities
• Storage loss will be high
• Public problems will come due to high population of insect pests inside the godown.

1.4.2. Procedure for undertaking prophylactic spraying inside the godowns:

Need identification Spraying shall be on the basis of
requirement fortnightly prophylactic treatment
i) air-charging of empty godown space before storage of food grains
ii) post fumigation spray
Preparation for i) Identification of area / volume to be sprayed
spraying ii) Calculation of correct dosage of required pesticide
iii) ensure availability of good spraying equipment (Knapsack/foot
sprayer/power sprayer)
iv) Prepare the pesticides with correct volume of water and ensure
that the pesticide is mixed properly with water
v) Sprayer should be of good one without any leakage and clear
nozzle for effective spraying.
vi) While using wettable powder formulation, uniform mixing
shall be done to avoid accumulation of powder at the bottom of
sprayer. This will lead to inefficient spray, patches on the bags
and walls and is likely to induce resistance in insects.
Spraying process i) Spraying shall be carried out by using appropriate pesticide as
per the CIBRC recommendation with correct dosage. Uniform
spraying shall be done.
ii) Light and gentle spraying shall be done on bags without
drenching which will lead to moisture increase in the food
grains.
iii) Spraying shall be resorted to evening.
iv) For effective air-charging, the windows and ventilators shall be
secured with wire mesh permanently.
v) After spraying/air-charging, godown doors/shutters shall be
closed for 24 hours. In order to achieve this spraying shall be
 given regularly during week end so that transactions in the
godown will not be affected.
Calculation of Deltamethrin 2.5% WP
insecticide Frequency: once in 3 months
Dilution: 120 g in 3 litre of water
Dosage: 3 Litres/100 sq.m. for surface treatment on bags containing
stocks, wall and alleways.

Preparation for i) Before undertaking spraying the area for treatment shall be swept,
spraying cleaned and spillage shall be collected to avoid contamination with
insecticides.
ii) The nozzle and delivery pipe of spraying machine should be
checked for blockage and leakage.
iii) Spray solution shall be prepared by mixing correct dosage of
insecticide in required quantity of clean water
Spraying process Spraying shall be carried out by the experienced personal by using
good sprayer preferably in the evening.
Post spraying activity The exit door shall be closed and sealed after spraying.
ii) Excess/unused pesticide solution shall be used outside on
platform/verandah or tree barks
iii) The delivery pipe, tank, nozzle etc. has to be cleaned with running
clean water

1.4.5. Precautions to be taken:

• Personal protective equipment (PPE) like hand gloves, eye-shield, gum boots and nose
mask should be used during handling and spraying of pesticides.
• Before spraying, the sprayer and its nozzle shall be checked thoroughly. Nozzle and
lance should not be blown with mouth.
• Spraying should not be done alone
• Spraying against the direction of wind should not be done
• While spraying movement shall be backwards to avoid body contact with treated area
• Eating, chewing, drinking or smoking should be avoided while spraying
• Along with personal protective equipment, the person spraying should wear aprons.
 • After spraying, hands and other parts of the body should be thoroughly washed with
soap & water
• The empty pesticide containers should be crushed and disposed of as per insecticide
act, 1968.
• Godowns should be kept open for few hours before entry so that accumulated chemical
fumes are diffused out
• In case of giddiness/headache, the affected person shall be taken out in fresh air and
shown to a physician if required.
2. Curative Measures

This is being done with using Aluminium phosphide 56% Tablets

Work Procedure:

Activity Description
2.1 Calculation of For cover fumigation – 9 g/MT (3 tab/MT)
Aluminium phosphide For shed fumigation – 360 to 420g /100 m3
Tablet
2.2 Exposure period 7 days for all storage pest
10 days for Leamophloeus sp.
2.3 Fumigation process a) Cover fumigation
i) Take the required quantity of Aluminium phosphide
tablets as per the dosage mentioned above.
ii) Install monitoring tubes on top back, middle and front
side of the stack and fold and clip the edges at bottom.
iii) Distribute the pre-calculated dosage in 6 to 8
enamelled/paper plates of at least 9” diameter spreading
the tablets in single layer and keep them at different
locations including beneath the crates, sides & top of
stack. 3 – 4 tablets can be kept in between the bags using
paper bag/cloth bag.
iv) Spread the fumigation cover on the top of stack and
then cover the stacks. Ensure that the cover is a sound one
 not torn or having holes.
v) Seal the fumigation cover on the floor level using sand
snakes to prevent leakage of phosphine gas. The cover
shall be secured in such a way it should be in tight with
stocks. Loose cover or oozing shall be avoided.
vi) Check the gas leakage on all sides using phosphine gas
leak check detector.
vii) Monitor the phosphine gas concentration regularly by
attaching the tubes fixed before fumigation at top, middle
and front side of the stack, using Phosphine gas monitor.
viii) For effective control the phosphine gas concentration
shall not be less than 760 ppm/m3

b) Shed fumigation
i) Take the required quantity of Aluminium phosphide
tablets as per the dosage mentioned above.
ii) Seal all the window panes, ventilators and doors except
exit door.
iii) Distribute the tablets on a paper plate and keep it at
different places uniformly on the stackes
iv) After placing tablets, ensure that no one is present
inside the shed. The come out and close the exit door and
seal it.
2.4 Post fumigation i) Remove the cover after completion of exposure period
operations and fold it properly
ii) Take representative sample from the stack and check
for live insect, if any in order to ensure the fumigation is
effective.
iii) Brush the bags thoroughly and clean the godown to
remove dead insects and residual powder within 2 days.
iv) Spray with malathion at recommended dosage as post
fumigation spray.
2.5 Precautions:-

• Personal protective equipment (PPE) like hand gloves, eye-shield, gum

boots, face mask with canister etc., should be used during handling and
application of fumigants.
• Check the fumigation covers for cut, holes etc., and resort to repairing, if
needed before putting on the stack
• Leave the site of fumigation as soon as the process is over
• Display ‘DANGER’ symbols on the fumigated stack and exit door of the
shed.
• Entire operation of fumigation should be carried out in the presence of
technical in-charge and supervision of accredited fumigation operator under
NSPM 22
• Fumigation should not be done alone
• Eating, chewing, drinking or smoking should be avoided during application
of fumigants and while de-gassing
• The empty pesticide containers should be crushed and disposed as per I.A
1986existing guidelines
• Godowns should be kept open for few hours before entry so that accumulated
chemical fumes are diffused out
• In case of giddiness/headache etc., the affected person shall be taken out in
fresh air given first and shown to a physician if required.
• In case of gas leakage indicated by characteristic smell, strengthen the
sealing.
• Roof leakage should be avoided by appropriate sealing of leakage points
there in the godowns where fumigation with Aluminium phosphide is
undertaken.
• Always keep the firefighting equipment ready as the gas is inflammable
during the process of fumigation.
• The fumigant should not be handled with empty hands.