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Maize weevil: threat to stored maize
In India, maize is emerging as the third most important crop after rice and wheat. Maize has its significance as a source of a large number of industrial products besides its use as human food. Maize does possess tremendous potential in terms of feed for dairy, poultry and piggery. Maize seeds are often stored for 3 to 5 months period for getting affordable price at traders and farmers level.
Serious pest
During this time, maize weevil, is a most serious storage pest which causes considerable losses. In tropics, weevils often lay eggs in the ripening crop before harvest and these develop and multiply during storage.
Adults are small, reddish brown in colour. Females make a small hole on the grain, lay 60 to 400 eggs over a period of 4-5 months, one egg per cavity, and seal each hole with a plug of gluey secretion.
Eggs are white in colour and hatch in a few days and the grubs feed inside the grain and destroy the interior of the grain. Grubs are white with yellowish brown head. Pupation occurs within the grain kernels and emerge through an irregular hole made on the grain. The entire life cycle is completed in about a month.
Both grubs and adults cause the damage. Grains are hollowed out and kernels are reduced to powder form. Because they feed on whole grains, these insects are more likely to be a problem in grain bins and warehouses and in kitchens.
Grains should be stored after proper drying. The gunny bags in which the grains are to be stored should also be dried properly.
Useful gadgets
During the storage period, monitoring can be done for the insect presence through the following Tamil Nadu Agricultural University (TNAU) gadgets such as Probe trap, Pit fall trap, Automatic Insect Removal Bin, Indicator Device
Based on the indications and the emergence of field carry over population of adult weevils, periodical drying should be done.
Zadda
KAVITHARAGHAVAN & S. MOHAN
Department of Agricultural Entomology
Tamil Nadu Agricultural University, Coimbatore – 641 003
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