Effeet of Verfieillium Leeanii Entomopathogen of the Whitefly Trialeurodes Vaporariorum on the Para Sitie Aetivity of Amifus Fuscipennis in a Bean Eulture

In order to evaluate the effect of the entomopathogen Verticillium lecanii against the whitefly parasitoid A. fuscipennis bioassays were performed under greenhouse and field conditions. Greenhouse bioassays were carried out at 70% relative humity and 25°C of temperature. The parasitoid A. fuscipennis was introduced 0,24,48 y 72 hours alter the application 01' V. lecanii in bean leaves containing whitel1y nymphs of second instar. Under these conditions the fungus V. lecanii decreased the parasitic activity of A. fuscipennis with the course oftime. When the parasitoid was introduced immediaiely after the fungi applications, A. fuscipennis parasitisrn percentage was 19%, and after 24 hours parasitism level was 10%. The activity of A. fuscipennis to parasitize whiteflies decreased at 0.5% after 48 and 72 hours of entomopathogen application. In spite of decrease of A. fuscipennis parasitic activity, V. lecanii never infected directly the beneficial insect A. fuscipennis.

For the fields assays the entomopathogen was appl ied every 10 days for 80 days after sowning. These applications were performed as two preforrnulations of V. lecanii developed by Corpoica, and as a cornmercial product based on V. lecanii recornended for whiteflies control (Vertisol). This experiment also included an absolute control and a treatment of Integrated Pest Management (MIP) that consisted in the aplication of a granular insecticide during the sowing, the use of yellow and adhesive trap and the application of chernical insecticide when the damage level increased. The statistical analysis for the results showed significant diferences between all evaluations and the one made after 40 days of sowing, Corpoica preformulátions did not affect significantly the parasitism activity of A..fitscipennis.

The percentage parasitism obtained when these products were used was 15 %, whereas cornmercial treatment (Vertisol) reduced A. fuscipennis parasitism level at 7% in contrast with MIP treatment that showed a A. fuscipennis level of parasitism of 17% while absolute control showed a parasitism of23%.