Effect of synthetic pyrethroids and other compounds on the susceptibility and development of the egg stage of the predacious miteAmblyseius gossipi [Mesostigmata: …

Abstract

Eggs from a laboratory culture of Amblyseius gossipi El-Badry laid on cotton strands were placed on leaf discs and sprayed with various pesticides or water for 40 s. The eggs were allowed to dry and then transferred to new discs. Compounds tested were cypermethrin, flucythrinate, fenvalerate, cyfluthrin, pyridaphenthion, methamidophos, dichlorvos and dicofol. Only methamidophos was inactive on the egg stage. When sprayed at a level of 400 ppm, eggs were highly susceptible to flucythrinate, cyfluthrin, pyridaphenthion, and fenvalerate and were slightly susceptible to dichlorvos and dicofol. Viability of eggs decreased as the concentration of the effective compounds increased. Older eggs were more sensitive than younger ones. None of the larvae from eggs treated with flucythrinate and pyridaphenthion were able to develop beyond the larval stage.