Comparison between the toxicity of synthetic pyrethroids and other compounds to the predacious miteAmblyseius gossipi (Mesostigmata: Phytoseiidae)

Abstract

This work involves a comparison between the toxicity of four synthetic pyrethroids (cypermethrin, flucythrinate, fenvalerate and cyfluthrin), two organophosphorus compounds (pyridaphenthion and methamidophos) and a chlorinated hydrocarbon (dicofol) to the predacious miteAmblyseius gossipi El-Badry. Direct application of cypermethrin, flucythrinate and fenvalerate was moderately toxic to the adult females, while cyfluthrin was highly toxic. The most toxic compounds were pyridaphenthion and methamidophos, while the least toxic was dicofol. Residues of the synthetic pyrethroids, even at a non-toxic level, interrupted oviposition and decreased reproduction dramatically. Ingestion of cypermethrin, cyfluthrin and pyridaphenthion did not significantly increase mortality but significantly decreased the daily average egg production. In the case of cypermethrin and cyfluthrin, an increase in consumption of treated prey per day increased mortality at the higher density while egg production progressively decreased with cypermethrin, cyfluthrin and pyridaphenthion respectively.