Toxicity of Citrus Pesticides to Some Predaceous Phytoseiid Mites1

Abstract

The relative toxicity of pesticides to adult predaceous phytoseiid mites in relation to plant feeding mites was evaluated by the slide dip technique. The toxicity ratios of Typhlodromus occidentalis Nesbitt, Amblyseius hibisci (Chant), A. stipulatus Athias-Henriot, Iphiseius degenerans (Berlese), and Phytoseiulus persimilis Athias-Henriot were compared to Panonychus citri (McGregor) or Tetranychus pacificus McGregor. T. occidentalis was more resistant to many of the pesticides than the plant feeding mites; the other 4 species of predators were generally more susceptible to the pesticides than P. citri or T. pacificus . Azinphosmethyl and Vendex® (hexakis (beta, beta-dimethylphenethyl)-distannoxane) had similar order of toxicity to the 4 predaceous species as the plant feeding mites, and tricyclohexylhydroxytin was less toxic to all 5 predaceous mites than to P. citri or T. pacificus . A. hibisci eggs were exposed to concentrations of citrus pesticides by utilizing the Potter Tower sprayer. A wide range of susceptibility of both eggs and immatures was shown to exist to the various pesticides evaluated. The egg stage was relatively tolerant to a number of the pesticides evaluated. Propargite and Vendex residues were the least toxic to the immature mites.