Connecting pest management with behavioral autorecognition of pheromone lures in insects

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Alison R. Gerken and James F. Campbell, ARS, USDA, Manhattan, KS, Shelby Abts, Kansas State University, Manhattan, KS

Background/Question/Methods
Mating disruption has been used as a pest management tactic for several insect species that infest stored grain products. The use of pheromone lures has been modeled and discussed in the context of male response, as the pheromone is often sex based. However, the response of females to increases in pheromone within their environment has not been studied as extensively. If females have significant autorecognition of pheromones, meaning a change in their behavior based on pheromone exposure, this may affect the use of mating disruption in these insect pest systems. By understanding the female response to pheromones, pest management mating disruption programs may be realigned to increase efficiency, ultimately decreasing the number of mating events and the population over time. In addition, we want to understand how the time spent in laboratory culture could influence behavior. In our experiment, we analyzed the fine-scale behaviors associated with Indianmeal moth, Plodia interpunctella, of two different strains, one collected in 2017 and the other in 2019. We exposed females of these strains to synthetic pheromone lures and quantified how differences with and without exposure to pheromone could impact mating disruption and how the two different strains could indicate subtle behavior differences among populations.

Results/Conclusions
Results indicate that the 2017 strain called (released pheromone) significantly less often and for shorter durations than the 2019 strain (p < 0.001). The 2017 strain spent significantly less time walking (p = 0.0088) when exposed to pheromone lures but did not have differences in cleaning (p = 0.33) or calling behaviors (p = 0.22). However, females of the 2017 strain exposed to pheromone started calling significantly later into the assay than did control females (p < 0.0001). Similarly, females of the 2019 strain also spent less time walking when exposed to pheromone (p = 0.0018) and spent more time cleaning (p = 0.0027) when exposed to pheromone lures. These results indicate that there is autorecognition of pheromone lures by these females and that this behavior could play a role in the use and distribution of pheromone for mating disruption throughout a treated space. The arrestment of behaviors due to exposure to pheromone could decrease chances that males and females will randomly encounter each other and increase chances of mating disruption success. Further experiments varying the spatial variation of pheromone lures to females provide additional quantification of this behavioral phenomenon.