The feeding behaviour of Phytoseiulus persimilis (Acarina: Phytoseiidae), particularly as affected by certain pesticides

Detailed observations were made of the behaviour of Phytoseiulus persimilis while searching for, identifying and feeding on eggs of Tetranychus urticae. A theory is proposed to explain how P. persimilis may identify prey eggs and distinguish them from non-prey objects. The existence of a water-soluble feeding stimulant on prey eggs is postulated. The effect of residues of captan, dinocap and malathion on the feeding behaviour of P. persimilis was investigated. Residues of the fungicide dinocap on the eggs of the prey did not affect acceptance by the predator, but captan had a marked repellent effect. Malathion had an even stronger repellent effect. It is suggested that, by making the prey eggs less acceptable to the predator, the use of certain fungicides could render more difficult the prediction of population interactions on which biological control depends. We wish to thank Dr N. W. Hussey of the Glasshouse Crops Research Institute for helpful comments and for supplying predatory mites. Mr Jackson wishes to thank the Overseas Development Administration for financial support during this work.