Control of moths in stored grains

The Angoumois grain moth is the most serious pest injurious to rice, both in the field and storage.

This moth also attacks other cereals like maize, wheat and sorghum.

The infestation may reach serious levels before the grains are transported to the storage godowns resulting in around 25 per cent loss in weight and seed viability.

Internal pest

The larva is an internal borer of the whole grain, feeding on the starchy part. Severely infested material emits an unpleasant smell and looks unhealthy in appearance.

Grains are often covered with scales shed by the moths. The grains are practically hollow and filled with larval excreta and other refuse making it unfit for consumption.

The adult is a small, straw coloured moth. The female can lay an average of 150 eggs on unhusked paddy grains.

They hatch in a week’s period. Newly hatched caterpillar is yellowish white in colour with a brown head capsule. It soon bores into the grain and feeds on its contents.

Larval stage lasts for about three weeks. Before pupation, the larva constructs a silken cocoon in the cavity made during feeding and turns into reddish brown pupa.

After a period of 4-7 days, the adult emerges. Entire life cycle is completed in 30-35 days.

Several generations are completed in a year. Adults are short-lived and can be seen flying about in large numbers in storage bags and on the surface of grains.

Management

— Drying the grains under sun for three days to reduce moisture content below 12 per cent is suggested.

— The jute bags to be used for storing grains have to be dipped in insecticidal solution of fenitrothion 50EC at 5ml/20 liters of water.

— Application of dichlorvos (DDVP) 76SC is recommended on the surface of stored jute bags by dissolving 7ml/lit. of water and the spray solution is sprayed at three lit/100 sq.m.

— Male moths can also be caught in sticky traps baited with female sex pheromone.

Mr. Jayaraj (Author)

About Author:

J. Jayaraj, associate prof and R.K. Murali Baskaran Professor & Head, Dept of Entomology, Agricultural College and Research Institute, Madurai 625 104, email: vu2jrj@rediffmail.com, phone: 0452- 2422956 Extn: 214

Source of Article:The Hindu