Acute toxicity of fenpyroximate to Amblyseius swirskii (Acari: Phytoseiidae)

Alternative pest management techniques such as biological control are promising components to many integrated pest management (IPM) programs. Knowledge about the effects of pesticides on biological control agents is required in order to successfully implement these programs. The predatory mite Amblyseius swirskii Athias-Henriot has been widely used to control major pest species in vegetable production. Evaluations of the side-effects of different pesticides on the performance of this predator have been made; however, effects of fenpyroximate, an acaricide/insecticide commonly used by Florida vegetable producers, have not been evaluated. The effect of four residual concentrations of this compound on adult A. swirskii females, its effect on their fecundity (number of eggs laid) and larval survival was measured under laboratory conditions. Distilled water was used for the controls and mites were checked in a daily basis for five days. Fresh residues of fenpyroximate were significantly toxic to adult females and larvae. Mortality increased as the concentration of the insecticide and time after treatment increased. Fecundity decreased as the concentration of the compound and time after treatment increased, probably due to the high mortality of females. 50% of the larvae survived in the two lower concentrations. They were found active and feeding indicating that A. swirskii populations might recover from the acaricide application if they molt into adults and reproduce. The present study is just an approximation of the toxic effects of this acaricide but more evaluations including other sublethal effects and population dynamics are required to clarify the level of compatibility of fenpyroximate to this phytoseiid specie.