Investigations of the chemical control of insect pests of cotton in central Africa. I.—Laboratory rearing methods and tests of insecticides by application to bollworm eggs

Abstract

Cotton in Central Africa is subject to attack by numerous insect pests, and this has limited production. The pests include Diparopsis castanea Hmps., Heliothis armigera (Hb.), Earias spp. and Dysdercus spp. Methods of rearing these insects in the laboratory are described, preparatory to testing insecticides for their control. By means of an egg-dipping technique, the susceptibility of first-instar larvae of Diparopsis castanea to a wide range of insecticides was determined, and that of similar larvae of E. biplaga Wlk. to a smaller range. The most effective were methyl-parathion, carbaryl, menthyl-demeton, parathion, methiocarb, Zectran, isobenzan, endosulfan, BHC, endrin and phosphamidon. DDT was more effective against Earias than against Diparopsis, and toxaphene was relatively ineffective against both. Aftertakiing the mammalian toxicity of the insecticides and certain other factors into consideration, carbaryl, endosulfan, endrin and DDT were selected for further evaluation in the laboratory and the field.