Behavioral Responses of the Social Wasp Polistes myersi to Prey Infected with Fungi Used in Biological Control

Metarhizium anisopliae and Beauveria bassiana are commonly used entomopathogenic fungi, but their non-target effects over generalist predatory insects, which can contribute to pest control, are not well known. We studied the capacity of the social wasp Polistes myersi to detect the pathogens in either a powdered form or in Galleria mellonella larvae infected with either of the two pathogens offered as prey. The effects of these treatments were compared considering wasp behaviors such as prey preference, frequency, duration and transitions of both hunting and grooming behaviors. Additionally, the effects of each entomopathogenic fungus on the wasp’s mortality were measured. Wasps seem not to detect the pathogens in powdered form but preferred healthy over infected larvae. Seventeen behavioral units for hunting and 34 for grooming were recognized. There were no differences in grooming frequency but there were significant differences on grooming duration, hunting behaviors and the patterns of transitions. Exposure of wasp colonies to either B. bassiana or M. anisopliae had no detectable impact on the mortality of adults, but mortality of larvae increased. For the first time, this study documented behavioral changes that indicated the capacity of social wasps to detect pathogens before physical contact and the display of hygienic strategies once contact occurs. The study also suggested a potential non-target effect of these entomopathogenic fungi on a generalist predator.