Toxicological Studies on the Egyptian Cotton Leafworm, Prodenia litura. III. A Modified Technique for Testing the Stomach-Poisoning Effect of Insecticides on Leaf-Feeding Larvae1

Abstract

A simple sandwich technique for testing the stomach-poison toxicity of synthetic organic insecticides on leaf-chewing larvae is described. Fourth instar Prodenia larvae were used. The dose of the insecticide in acetone solution was applied to the sandwich, using a 1-μl glass micropipet. Castor oil leaves were cut into small discs to form the sandwich. The 2 discs containing the insecticide on the inner surfaces were stuck together with a pectin paste fortified with sugar. The technique ensures no contact between the feeding larva and the insecticide, Precise determination of the dose each larva ingests is easily determined.