Effects of sublethal permethrin exposure on larval Culex pipiens response to conspecific alarm cues

Organisms living in aquatic environments rely on olfactory, or chemical, information to assess predation risk in environments that are often turbid and difficult to navigate. Utilizing olfactory signals and cues enables aquatic prey to assess predation risk and grade antipredator responses to match the perceived degree of risk, which can improve survivability and fitness. Today, many aquatic habitats can become contaminated with lethal or sublethal concentrations of pollutants and pesticides which, in turn, could influence predator-prey dynamics. The purpose of this study was to examine the behavioral response of larval Culex pipiens to a simulated predation event by introducing conspecific alarm cues following exposure to sublethal concentrations of the insecticide permethrin. Larval responses were analyzed for three common antipredator behaviors comprised of distance traveled, mean velocity, and change in mobility. While permethrin exposure resulted in no significant change in behavioral response, significant differences were noted in response to the presence of aqueous extracts from crushed conspecific larvae. Although permethrin exposed larvae did not exhibit statistically significant differences in response to alarm pheromone, a trend showing incrementally smaller intensities in behavioral responses could be seen with increasing concentrations of alarm cue. This research demonstrates that even low concentrations of permethrin exposure can influence larval Culex pipiens behavioral response to conspecific alarm cues which could have meaningful implications for larvae existing in predator rich environments contaminated with pesticide