Biopesticide Exposure Increases Aggression Without Impairing Nestmate Recognition in a Social Paper Wasp

: Biopesticides have gained increased attention as sustainable substitutes for synthetic pest control products. Nonetheless, in recent years, a growing body of research has highlighted their undesired effects on non-target organisms, including sublethal impacts on social behavior. Here, we investigate the potential adverse effects of a common biopesticide, the entomopathogenic fungus Beauveria bassiana, on the nestmate recognition ability of the paper wasp Polistes dominula. Nestmate recognition, based on individual cuticular hydrocarbons (CHCs) profiles, plays a key role in the colony integrity of social insects, avoiding foreign intrusion and the spread of pathogens inside the nest. P. dominula workers were topically exposed to the biopesticide, and subsequent presentation behavioral assays and GC-MS chemical analyses were carried out to evaluate possible changes both in the nestmate recognition ability and chemical profile induced by B. bassiana. Biopesticide exposure altered the CHCs profile of exposed wasps and triggered increased aggression toward both exposed nestmates and foreign individuals, while not disrupting the colony nestmate recognition system. The higher aggressive response toward exposed wasps likely represents an adaptive strategy to prevent the entrance of pathogen-infected individuals into the nest. The present study demonstrates how an integrated approach based on behavioral bioassays and chemical analyses can effectively evaluate the sublethal effects of plant protection products on non-target organisms.