Behavioural changes in Eretmocerus mundus (Hymenoptera: Aphelinidae) by insecticidies action

NATALIA FRANCESENA; SMAGGHE GUY; STADLER TEODORO; SCHNEIDER MARCELA INES

Simposio; 66 th International Symposium on Crop Protection; 2014

Knowledge about the impact of insecticides on the natural enemies of agricultural pest is relevant for the integration of biological and chemical control. Assessment of sublethal effects of insecticides on natural enemies is necessary to recognize the whole impact of these products. Sublethal effects have been defined as effects on organisms that survived pesticide exposure. These may be manifested as a reduction in life span or stage developmental time, fecundity and fertility, sex ratio changes in the progeny or behavioral changes in organisms exposed. The objective of this work was to evaluate the side effects of four biorational insecticides (acetamiprid, azadirachtin, piriproxyfen and spirotetramat) and one conventional insecticide (cypermethrin) on the behavior of Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) adults, the main parasitoid of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) worldwide. Laboratory bioassays were conducted to test the sublethal effects of each insecticide. Treatments consisted of a solution of each insecticide in distilled water, at the maximum field recommended concentration (MFRC) and half of the MFRC. Controls were exposed to distilled water alone. Sweet Pepper (Capsicum annuum L.) leaves discs (2cm diameter) were dipped in the treatments for 10 seconds and dried under fume hood. Parasitoids (1-3 days old) were exposed to the treated sweet pepper leaves by residual way for one hour, and observed under binocular microscope and filmed for 9 minutes to record their behavior. The following behaviors were recorded: walking, feeding, grooming, contact and search on the treated surface, tremors and knockdown or excitation effects. Twenty replicates were done for each treatment tested. All tested insecticides affected parasitoid behavior (at least one of the behaviors measured were modified) at both concentrations tested. Cypermethrin and acetamiprid displayed the strongest effect where tremors, knockdown or excitation effect were the most frequent behaviors observed. Azadirachtin and pyriproxyfen showed an intermediate effect on the parasitoid behaviors evaluated, where the grooming behavior was recorded more often than in the controls. In contrast, spirotetramat showed no significant effect on the parasitoid behavior in comparison to controls. Results suggest that E. mundus adults are susceptible to four of the five insecticides evaluated. Further studies are needed to determine additional sublethal effects in order to complete the toxic profile of these insecticides.