2.1.2 Insect infestation and its control
This can be tackled by complete wiping out of the existing insects and safe guarding re- infestation. These insects can multiply very fast under favourable conditions. For example, a small population of the flour beetle can multiply to 76 million within a period of six months at 28oC temperature and 65 to 80 per cent relative humidity. If infestation is heavy, the crawling insects can be detected on the bags, in between stacks, on floors and walls of the godown. To assess the extent of infestation about 3 kg samples should be collected from different stacks, sieved and examined. Table 2.1 may serve as a general guideline for insect infestation.
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Table 2.1 General guidelines for insect infestation |
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Clean |
No insects in stacks or in the sieved sample or the sample incubated for 3 weeks |
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Light |
2 to 3 adult insects in the sample with 1 per cent damaged grains |
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Medium |
5 to 10 adult insects with 3 per cent damaged grains |
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Heavy |
Crawling insects on the stacks, 10 to 20 adult insects in one kg sample, 5 per cent damaged grains |
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Very heavy |
10 to 20 adults in 100 g sample. A rustling sound of insects can be heard near bags. Crawling insects on floor and walls |
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Table 2.2 Common insects found in cattle feed raw materials |
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Popular name |
Product in which generally found |
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Rice weevil (Sitophilus spp.) |
Maize, sorghum, wheat bran, rice polish, cowpea |
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Lesser grain borer (Rhyzopertha spp.) |
Rice polish, pulses, tapioca |
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Warehouse beetle (Trogoderma spp.) |
Groundnut |
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Flour beetles (Tribolium spp.) (bran bugs) |
Maize gluten, cakes, meals, brans and polishes |
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Flat grain beetles (Cryptolestes spp.) |
Maize, rice and wheat |
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Grain moth (Coreysa spp.) |
Maize, wheat, milo and rice |
Control of insect infestation
i) Spraying: Spraying can be done to control light infestation. DDT/ lindane formulation, malathion, DDVP (Nuvon) are the usual insecticides used for spraying. DDVP can be used as 300 ppm solution to spray over the stacks and malathion 5per cent can be sprayed on the floor and walls ups to 9 ft. height.
ii) Fumigation: In case of heavy and very heavy infestation fumigation is advised. For this the stacks is covered with aluminum coated rubber sheets to make the stacks airtight and fumigation is done by supplying fumigants (e.g. aluminum phosphide) to the stacks.
Some of the fumigants used in cattle feed plants are listed below:
• ED:CT mixture 30 to 35 tables / 1,000 sq. ft. for 48 hours every 3 months.
• EDB and MB mixture 1 to 3 tables/1,000 cu ft.
• Celphos tables – 2 tabs/ton
• 16 per cent lindane in a smoke generator.
Precautions to be taken during the operation:
• No smoking
• Hand gloves, aprons, spectacles, gum-boots should be used
• Doors and windows should be kept opened.
Residual effect of pesticides and animal toxicity
Many pesticides have a residual effect. These residues at certain level may prove toxic to the animals. Thus these should be carefully used. Insecticides like ethylene dibromide, methyl bromide, aluminum phosphide, etc., generally have residual effect. The treated material should be exposed to air for some time before issuing for production.
Safeguard the infestation
It is better to adopt certain measures to prevent the store from infestation than to check it afterwards. Any raw material with moisture more than 10 per cent should not be stacked in the godown for longer period. The finished product should be free from feed dust or broken particles. Godown should be so constructed and stacking done in such a manner that cross ventilation is allowed. Cleaning of stacks and godowns should be done regularly.
Insecticides and pesticides residues
To control infestation of insects, pests and rodents in food grains, several insecticides, pesticides and rodenticides are used. The residues of these chemicals must be within the prescribed limits as per the Prevention of Food Adulteration (PFA) Act.
