Few insects can be mass reared in a laboratory without encountering problems. Difficulty is usually encountered in rearing the American bollworm (Heliothis armigera) in the laboratory because of the cannabalistic tendency of the larvae, their susceptability to disease, and unreliable oviposition. Reported herein are some modifications effected to the method descriptionbed by Bot (1966) which were found to be satisfactory, allowing a colony to be bred for four years without difficulty.
The distribution of Heliothis assulta afra (Hardwick), given by Hardwick (1965), showed this species to be relatively rare in southern Africa with only a few known localities. During 1970, a grid of light traps was established in South Africa and some specimens of H. assulta afra were caught. Dr. L. Vari (Transvaal Museum, Pretoria) confirmed the identity of the moths.
The organophosphate insecticides are used to control aï¿½ wide variety of insects. The majority are contact poisons but some are systemic. It is common knowledge that these compounds are potent inhibitors of cholinesterase, an ssential enzyme in the nervous system of all animals. We have made use of the acetyl cholinesterase-inhibiting properties of methyl demeton, a systemic organophosphate, to trace its uptake by young wheat plants. The method is essentially a modification of that descriptionbed by Gomori ( 1953).