Insecticide-mediated effects on mating success and reproductive output of Drosophila suzukii.

Exposure to sublethal concentrations can have adverse effects on certain individuals, but, can also favor survival and reproduction of others. This study aimed to evaluate the effects of exposing Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae) adults to LC50 of spinetoram and lambda-cyhalothrin and field rate of thiamethoxam on their mating, reproductive output and longevity. The LC50 for lambda-cyhalothrin and for spinetoram were 7.83 and 32.91 ng a.i./cm2, respectively. Thiamethoxam, in the concentrations tested, was not toxic to D. suzukii, therefore, we use the recommended concentration for strawberry, 231.25 ng a.i./cm2, in the sublethal tests. Insects exposed to LC50 of lambda-cyhalothrin were more likely to mate, but presented shorter copula. Sublethal exposure to thiamethoxam lead to an increase in total fecundity. Among the insecticides tested, spinetoram presented the least expressive effects. Longevity was not affected by any of the tested insecticides. Results presented in this study are relevant to D. suzukii management since the stimulatory effects shown on this pest species can collaborate to outbreaks and insecticide resistance.