The Insecticidal Properties of Some East African Plants. I.

Abstract

A number of East African plants, mostly indigenous, has been tested for insecticidal value as contact poisons. No new insecticide equal in toxicity to nicotine has been discovered. Two plants, Cassia didymobotrya and Barringtonia racemosa, have toxic properties slightly less than half that of nicotine used as sulphate. The plants, which grow dd, should be of value for making insecticides on those farms where they are already growing: they would not, however, be worth cultivating. No definite chemical compounds were obtained from these two plants. The toxicity of extracts of Tephrosia vogelii has been found to be of the same order as that of nicotine in the form of sulphate, and these extracts should be able to replace nicotine in all sprays against soft-bodied insects such as aphis and thrips.