Further non-target effects of citrus pesticides on Euseius addoensis and Euseius citri (Acari: Phytoseiidae)

A series of leaf-disc bioassays were conducted to determine the detrimental effect of field-weathered residues of various pesticides used on citrus in southern Africa on the adult females of two species of Eusei us (Wainstein). Acaricides, insecticides and stem- or soil-applied systemics were tested against E. addoensis (van der Merwe and Ryke). Fungicides were tested against E. citri (van der Merwe and Ryke) because it is the dominant predatory mite on citrus in the regions where most fungicides are used. The residual toxicity and persistence of most acaricides and fungicides were relatively low. Aldicarb was the only systemic product to cause more than 5% mortality. The most detrimental insecticides tested were cypermethrin, formetanate, fluvalinate, omethoate plus mineral oil and fipronil. Of the insect growth regulators tested, diofenolan was the most detrimental. All the fungicides suppressed fecundity whereas most of the systemic products stimulated fecundity. The other compounds had variable effects on fecundity.