Bollworms Eariasvittella (Fabricius) and Eariasinsulana (Lepidoptera: Noctuidae) Impairment in Cotton and Integrated Crop Management

Abstract

This article focuses on bollworms Eariasvittella (Fabricius) and EariasinsulanaBoisduval, which are primarily insect pests of cotton and can make cultivation of crop nearly impossible in some years. Initially, the caterpillars tunnel into buds by destroying vessels and growing points, they cause adjacent blooms, young leaves and eventually whole shoots to turn blackish-brown and die off, which can result in bunched growth of young plants. Examination of the affected plant parts reveals a number of small holes either on or near to leaf, or flower buds. On cotton, the damaged flower buds sometimes spread their bracteoles prematurely (flared squares). When fruiting starts, the larvae turn towards the bolls, which as a result then become brown and fall off. Older bolls may stay on the plant, but are often so damaged that they cannot be harvested. Secondary invasion by fungi and bacteria sometimes occurs, and ultimately damage and excrement-filled tunnels in surviving fruit result in a low market price. Management of Eariasbollworms is becoming increasingly difficult due to the development of their resistance to many chemical insecticides. In view of these facts, it is needed to develop eco-friendly tactics such as Integrated Pest Management (IPM) program wherein all practicable tactics are implemented. Setting of light trap or pheromone traps at 12 per ha at 40-45 days can effectively monitor adult’s activity.Pheromone trapping data on bollworms give early warning of the infestation and also exhibit the density of the insect population.Biological control and botanical pesticides are economical and safe to the environment. The egg parasitoidTrichogramma chilonisis the most widely exploited hymenopteran parasitoid by releasing at 1, 25,000 perha three times in a crop to control the bollworms. The infested fruits and shoots should be removed regularly and buried deep in the soil. Spraying with quinalphos 25 EC (2 ml per liter of water) or carbaryl (4 g perliter of water) effectively controls the pest. Before spraying all the affected plant parts should be removed.After harvest, cotton plants which can sprout from the stump should be uprooted and destroyed in order to eliminate the food source for Earias spp., and thereby to interrupt population build-up.