Como o inseticida Fipronil pode impactar colônias da vespa social Polybia paulista

Abstract

Phenylpyrazoles (fipronil) are a group of insecticides widely used for managing insects considered agricultural pests, due to their neurotoxic action and systemic effects on plants. However, there are no studies investigating the consequences of their use on social wasp colonies. Social wasps are generalist predators and play an important role in biological control of pest insects. In addition, they provide pollination services and may even surpass bees in both abundance and species richness as floral visitors. However, by visiting and consuming floral resources, they are also exposed to insecticides used in crops, thereby entering the same contamination pathways as bees. The objective of this study was to identify the median lethal concentration and evaluate the effects of exposure to sublethal concentrations on the survival of foragers of the social wasp Polybia paulista to the insecticide fipronil. To obtain the median lethal concentration (LC₅₀), the wasps were exposed to different concentrations of fipronil, and the LC₅₀ obtained was subsequently used as a reference for obtaining the sublethal concentrations. For survival analysis, groups of control wasps and groups of wasps exposed to sublethal concentrations were monitored until death, and the median lethal time (LT₅₀) was then calculated. The LC₅₀ after 24 hours was 0.890 ng a.i./μL (~890 ppb). Wasps exposed to any of the sublethal concentrations survived for a significantly shorter time than those in the control group. Therefore, we conclude that exposure to fipronil affects the survival of P. paulista foragers as much as the neonicotinoid insecticide thiamethoxam, and that social wasps may be as susceptible, or even more susceptible, to fipronil contamination than other commonly studied non-target insects.