Control of tobacco caterpillar in cotton
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The pests are gregarious feeders
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DURING PAST few years Helicoverpa armigera, called American bollworm, used to be a serious pest of cotton throughout the country creating havoc among cotton growers.
But another insect known as tobacco caterpillar, belonging to the same family as American bollworm, has become a matter of serious concern for all the cotton growers.
Dome shaped eggs
The insect tobacco caterpillar lays dome shaped eggs in clusters (200-300 eggs/female), which are covered with buff coloured scales on the underside of leaves. The eggs hatch in 3-5 days.
Larvae are light brown initially and later turn dark in colour. Larval duration lasts for 15-28 days.
Pupal stage
The pupation takes place in soil. The pupa is brown and 10-12 mm in length and lasts for 7-10 days. Adults are 20-40 mm in length.
The adult stage lasts for 9-10 days. It completes 6-8 generations per year. The pests are gregarious feeders.
At first they feed near the site of hatching in groups by making small holes and thereafter migrate to other leaves and feed in a solitary phase.
Gregarious feeding leads to skeletonisation of the leaves.
Pest Management
The insect initially feeds in gregarious phase. So the leaves with cluster of eggs or smaller larvae can be located easily, plucked and destroyed manually.
The insecticides, which are recommended for American bollworm control are not effective for controlling this insect.
Chorpyriphos 20 Ec at 2.0 litre per acre or acephate 75 sp at 800 gm per acre diluted in about 125 litres of water are found effective in controlling this pest.
RISHI KUMAR
Asst. Professor of Plant Protection, Krishi Vigyan Kendra Regional Station
Punjab Agricultural University
Bathinda, Punjab
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