Natural parasitism of Bemisia tabaci and Trialeurodes vaporariorum in an horticultural area of Sardinia, Italy.

A three-year survey was carried out in southern Sardinia (Pula, Cagliari) to assess natural whitefly parasitism on greenhouse tomatoes and to evaluate the contribution of parasitic wasps as biocontrol agents for Bemisia tabaci on other crops and weeds. The rates of apparent parasitism on protected tomato crops were low, reaching 18.8% in the most favourable of cases. The role played by parasitoids for the control of B. tabaci varied greatly among cultivated and weed species. Seven species of Aphelinid parasitic wasps were found to be associated with whiteflies. On this basis, the agroecosystem examined could be regarded as quite rich in terms of parasitoid species. This positive precondition did not, however, make a decisive contribution to whitefly management.