Influences of botanical pesticides and biological agents on Orius laevigatus – Frankliniella occidentalis dynamics under greenhouse conditions

We assessed the influence of nine biopesticides on adults and larvae of western flower thrips (WFT), Frankliniella occidentalis (Pergande) and its predator, the anthocorid Orius laevigatus (Fieber) under Mediterranean greenhouse conditions. Trials were carried out in a strawberry crop where both species had naturally established. Foliar sprays were applied weekly for one month. Treatments did not provide sufficient control of larval and adult F. occidentalis. The negative effects on the dynamics of the predator were evident only with the use of some specific products. The botanical insecticides rotenone and neem, and the nematode Steinernema feltiae (Filipjev) reduced O. laevigatus numbers, and these effect are evident in the adult stage of O. laevigatus. Such products have determined a reduction of the population of the predator from the first treatments even if the incidence was not very high. We conclude that the use of some botanical pesticides and nematodes against WFT is uneconomical and possibly disadvantageous where there is an established predator-prey population.