LABORATORY STUDIES ON THE CONTACT TOXICITY AND ACTIVITY IN SOIL OF FOUR PYRETHROID INSECTICIDES

Abstract

The spectrum of contact toxicity and activity in soil of four pyrethroid insecticides was assessed in the laboratory. Pyrethroids tested were: FMC 33297 (3-phenoxybenzyl (±)-3-(2, 2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate); Shell WL 41706 (alpha-cyano-3 phenoxybenzyl 2,2,3,3-tetramethylcyclopropanecarboxylate); Shell WL 43467 (alpha-cyano-3-phenoxybenzyl 2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylate); and Shell WL 43775 (alpha-cyano-3-phenoxybenzyl-2-(4-chlorophenyl)-3-methyl-1-butyrate). Chlorpyrifos and carbofuran, two broad spectrum contact and soil insecticides were included for comparative purposes. Spectrum of contact toxicity was determined using 24–48 h nymphs of the common field cricket, Acheta pennsylvanicus (Burmeister), 24–48 h onion maggot adults, Hylemya antiqua (Meigen), 3rd instar dark sided cutworms, Euxoa messoria (Harris), northern corn rootworm adults, Diabrotica longicornis (Say), and honeybees, Apis mellifera L. Crickets were used to assess insecticidal activity in soil relative to soil moisture, type, and temperature. The pyrethroids were effective contact insecticides comparable in toxicity and spectrum of activity to chlorpyrifos and carbofuran. They were particularly toxic to the darksided cutworm. They were less effective in mineral soil than chlorpyrifos. WL 43467 showed activity in mineral soil close to that of carbofuran, while the other pyrethroids were less active. Activity in soil was influenced by soil moisture and type. In contrast to the standard insecticides the pyrethroids generally showed a negative temperature coefficient of toxicity in soil.