Effects of abamectin and acetamiprid pesticides on the survival and behavior of Scaptotrigona aff. xanthotricha (Apidae, Meliponini)

Pesticides have been described as a major cause of bee mortality, and thus are predictors of population decline and decrease in pollination services. Standardized tests with Apis mellifera are already common, and there is a need to create adequate parameters for the native solitary and eusocial species of stingless bees. In this study, we evaluated lethal dosages (LD50 and LD90), lethal time (LT), and sub-lethal effects (SLE) of two pesticides used in soybean crops, abamectin, and acetamiprid, in Scaptotrigona aff. xanthotricha. All tests were performed through contact poisoning. The LD50 and LD90 for acetamiprid were higher than those obtained for abamectin. Survival analysis of S. aff. xanthotricha exposed to LD90 indicated significant differences between pesticides. The LT50 under abamectin (8.25 hours) was significantly lower than acetamiprid (14.25 hours). Considering the PER tests, our results suggest that positive responses to food offerings were reduced by pesticide effects. It was also observed that only the acetamiprid affected the locomotion of the bees. Our results revealed that both pesticides are highly toxic to S. aff. xanthotricha and that acetamiprid was the most toxic for all parameters evaluated.