Toxicity-Related Behavior in the Invasive Argentine Ant Linepithema humile Mayr in Response to Fipronil Exposure1

Ants self-organize through interactions between individuals (nestmates). Therefore, it is possible that slight changes in individual behavior play an important role in interactions between individuals and subsequently lead to colony-level responses to environmental changes. While conducting research on the control/eradication of the invasive Argentine ant Linepithema humile Mayr, we observed an unusual behavior (i.e., a mandible-opening behavior: a toxicity-related behavior) displayed by ant workers after exposure to the insecticide fipronil until death. Although this phenomenon might represent a symptom of exposure to a toxin, it is possible that mandible opening behaviors are performed for the secretion of pheromones. Therefore, further studies are needed to clarify why fipronil-exposed workers exhibit mandible-opening behavior.