Relative susceptibility of Haeckeliania sperata (Hymenoptera: Trichogrammatidae) to pesticides used in citrus and ornamental systems in Florida

This study was designed to evaluate the relative susceptibility of Haeckeliania sperata adults to pesticides used in citrus and ornamentals. Parasitoids were exposed to pesticide residues on leaf surfaces. Four concentrations of seven pesticides were included in the bioassays. The tested concentrations for each pesticide consisted of a dilution series using the label rate for field applications as the starting concentration. Lethal concentrations (LC50s and LC90s) were calculated 12 and 24 hours after parasitoids were exposed to the pesticides and lethal times (LT50s and LT90s) were estimated for each insecticide concentration. LC50s and LC90s of organophospate, carbamate and pyrethroid pesticides were less than one eight of the label rates. LT50s and LT90s of these insecticides were always less than 12 hours even at the most diluted solutions. Applications of these pesticides might have a strong negative impact on the natural control of D. abbreviatus by the introduced parasitoid. Commercial formulations of imidacloprid, avermectin, petroleum oil and a phosphonate fungicide allowed H. sperata to live longer compared with the previous pesticides, suggesting a certain degree of selectivity. Moreover, Haeckeliania adults exposed to lower concentrations than the recommended rates of imidacloprid, avermectin, petroleum oil and a phosphonate fungicide had a greater chance of survival than those exposed to the label concentrations. Using products that have less toxic effects on the introduced parasitoid will increase its chances to parasitize D. abbreviatus eggs. All tested pesticides had a negative effect on Haeckeliania’s survivorship. However, some pesticides caused significantly less harm to this parasitoid.