Effect of pesticide mixtures on the predatory mite Phytoseiulus persimilis A.H. (Acarina, Phytoseiidae) in the laboratory

The acaricide hexythiazox (Acorit^® SC, 100 g a.i.l^–1), the fungicide triadimefon (Bayleton spezial^® WG, 52 g a.i.kg^–1) and the insecticide heptenophos (Hostaquick^® EC, 550 g a.i.l^–1), were tested in the laboratory for their side-effects on the predatory mite Phytoseiulus persimilis A.H. The pesticides were either applied separately at a range of concentrations or in admixture to detached bean leaves using a Potter Tower to deposit 2 mg spray solution per cm². No significant differences in the mean mortality rate of the phytoseiid or in the mean reproduction per female was found between the different treatments. Total effect values ranged from 5.4 to 38.7% after separate application of the test products and from 8.9 to 25.5% after treatment with the various pesticide mixtures.