Sublethal effects of esfenvalerate residues on pyrethroid resistant Typhlodromus pyri (Acari : Phytoseiidae) and its prey Panonychus ulmi and Tetranychus urticae (Acari : Tetranychidae)

The effect of residues of esfenvalerate on oviposition of the resistant str ain of the predatory mite Typhlodromus pyri and its main prey, European red mite Panonychus ulmi and two-spotted spider mite Tetranychus urticae, were investigated. T. pyri showed a significant linear reduction in oviposition after 24 h in the presence of increasing levels of esfenvalerate residue a pplied at the field rate. Furthermore, when given a choice, T. pyri preferr ed to lay eggs on residue-free surfaces. Of the two prey species, only P. u lmi showed significant avoidance of increasing levels of residues of the fi eld rate concentration of esfenvalerate, as measured by runoff mortality, h owever both P. ulmi and T. urticae, when given a choice, showed a preferenc e for esfenvalerate-free surfaces. As with the predatory mite T. pyri, both prey species showed a significant linear reduction of oviposition with inc reasing esfenvalerate residues and a preference to lay eggs on esfenvalerat e-free surfaces. Esfenvalerate residues as high as 15X field rate were not repellent to pyrethroid-resistant T. pyri. The possible effects of these su blethal effects on predator-prey dynamics and implications for integrated m ite control programmes in apple orchards are discussed.