Laboratory Toxicity of Commonly-Used Pesticides in California Citriculture to Euseius hibisci (Chant) (Acarina: Phytoseiidae)1

Abstract

Laboratory bioassays were conducted on leaf discs to determine the impact of 20 pesticides on two strains of Euseius hibisci (Chant) colonized from citrus. The herbicides and fungicides tested were modestly lethal to both E. hibisci strains. However, paraquat, glyphosate, and dikar expressed toxicity to E. hibisci. Laboratory bioassays showed that E. hibisci’s tolerance to chlorobenzilate was moderate for both strains as compared with dicofol. Azinphosmethyl, methidathion, and sulfur exhibited moderate acaricidal activity to the RH strain as compared with our standard LAB strain. E. hibisci was very susceptible to methomyl. Dimethoate was the only OP which caused high mortality in both strains. Although the resistance level of the RH strain to dimethoate was considerably lower than the recommended field dosage, it was 22-fold that of the LAB strain.