Ascher, K.R.S., Department of Toxicology, Agricultural Research Organization, Volcani Center, Bet-Dagan, 50-200, Israel
Nemny, N.E., Department of Toxicology, Agricultural Research Organization, Volcani Center, Bet-Dagan, 50-200, Israel

The effect of diflubenzuron as a residue on glass or applied topically to Spodoptera littoralis larvae was investigated. Diflubenzuron was active as a residue on glass against 100 and 200 mg larvae; the toxicity of residues was identical whether a dispersable formulation or a wettable powder or the technical substance were used. By topical application, diflubenzuron had an ED50 for cumulative percentage mortality up to the adult stage of 004 and 0066 μg/larva for 100 and 200mg larvae respectively. Neither the site of the topical application nor whether the larvae were kept singly or in groups of ten after the treatment had an influence on toxicity. The data indicate that diflubenzuron has contact toxicity to at least one insect species as well as the known stomach poison action. Copyright © 1976 John Wiley & Sons, Ltd