Toxicity of synthetic pyrethroid insecticides to predaceous phytoseiid mites and their prey

Abstract

The toxicities of two synthetic pyrethroid insecticides (cypermethrin and fenvalerate) and azinphosmethyl to the predaceous mite species Typhlodromus pyri Scheuten, Typhlodromus occidentalis Nesbitt, Amblyseius fallacis Garman (Acari: Phytoseiidae) and one of their prey, Tetranychus urticae Koch (Acari: Tetranychidae) were determined by laboratory slide dip tests. Comparison of LC₅₀ values showed both synthetic pyrethroid insecticides to be considerably more toxic than azinphos-methyl to all three species of predator mites, although T. urticae was less susceptible. It is likely that recommended application rates of both synthetic pyrethroid insecticides will cause considerable mortality of predator mites in the field yet exert little mortality on T. urticae.