Biology, Ecology and Control of Kadam Defoliator Arthroschista hilaralis Walk. (Pyralidae, Lepidoptera) in Plantations in West Bengal

Large-scale plantations or kadam raised by the West Bengal. Forest Department during 1962-69, in their young stage, suffered severe defoliation damage from Artkroschista hiloralis. Ecological studies of this defoliator were made in a field insectary at Chilapata, Cooch-Behar Division (West Bengal) from August to November 1971 as well as at Dehra Dun (Uttar Pradesh) during 1970-71. The defoliator has a life-cycle of 21-26 days, completing 11-12 generations in a year. Pest population begins to build up to epidemic proportion after a good amount of rains during July-August. By September the pest population reaches its peak and by 1st week of October it begins to decline. The main contributing factor of population decline is the want of high humidity supported by heavy parasitism (ca 60%) by Apanteles balleatea. Severe defoliation retards growth of young plants (2-5 year old) and repeated defoliation results in stunted growth Two parasites, A. baltealea and Cedria paradoxa, are promising agents to check the pest population increase. For the control of epidemic, mass- breeding and reiease of these two parasites (biological control) and encouragement or introduction of plants that support the collateral hosts of defoliator's parasites in or around plantations have been recommended (cultural control). If these two measures prove inaadequate treatment with 0.1% thiodan (a selective killer) or 0.1% dieldrin or chlordane water emulsion may be resorted to (chemical control).