Sustainable carrot weevil management has eluded specialty crop growers for decades. One contributing factor is a lack of knowledge about the semiochemicals that influence carrot weevil behavior. We have observed carrot weevils aggregating at the base of parsley plants. However, it is unclear if chemical cues from conspecific weevils are driving this behavior. Pheromones of other weevil species have been identified by collecting and evaluating frass, and interestingly, carrot weevils deposit frass on host plants when feeding and laying eggs. By evaluating carrot weevil frass for potential pheromones, we may identify chemical cues that will improve the efficacy of monitoring tools for this insect. To determine if carrot weevil frass contains potential pheromones, we performed y-tube bioassays to assess male and female response to conspecific frass. We collected frass volatiles using single phase micro-extraction fibers and subjected these volatiles to GC-MS analysis. Preliminary results suggest that carrot weevil frass may contain attractive chemical cues. Sixty-nine percent of males chose mixed-conspecific frass. Additionally, 69% and 70% of males and females, respectively, chose virgin female frass. The frass volatile blend included plant volatiles and an unidentified ketone. Weevil pheromones are commonly ketones, and the presence of an unidentified ketone in the frass volatile profile warrants investigation. These preliminary results suggest that carrot weevils orient towards frass and that the frass volatiles are similar to host chemical cues. Additionally, the frass volatile profile contains an unidentified ketone. Determining the chemical cues that influence carrot weevil behavior is key to improving management.
