Toxicity of some insecticides to Tetranychus urticae, Neoseiulus californicus and Tydeus californicus

The spider mite Tetranychus urticae, the predatory mite Neoseiulus californicus and the unspecialised feeder Tydeus californicus are frequently encountered on vegetables. The direct and residual effects of six insecticides recommended for the control of aphids, whiteflies and thrips in vegetable crops were evaluated on these mite species in the laboratory. Pesticide effects was often favourable towards T. urticae and unfavourable towards N. californicus and T. californicus. Rotenone was more toxic to eggs than females of T. urticae, and was highly toxic to N. californicus and T. californicus. Pyrethrins and imidacloprid increased T. urticae fecundity but decreased fecundity of N. californicus. Beauveria bassiana was not toxic to T. urticae and T. californicus, but induced high mortality in the progeny of N. californicus. Azadirachtin and pymetrozine were the least toxic to T. urticae and N. californicus, but affected T. californicus progeny. Implications of this study for IPM tactics are discussed.