Attraction, mobility, and preference by a secondary stored product insect to microbially-mediated volatile emissions by fungi in grain

Little research has linked how specific fungal species affect the behavior of stored product pest, Lasioderma serricorne. Enhanced knowledge about attraction to microbially- produced volatile organic compounds (MVOCs) may be used to manipulate insect behavior. Our goals were to 1) isolate, and culture one fungal morphotype, 2) characterize the volatile emissions from grain inoculated by the fungal morphotype (A. flavus or Fusarium spp.) compared to unmanipulated and sanitized grain, and 3) understand how MVOCs from the morphotype affects mobility, attraction, and preference by L. serricorne. Headspace collection revealed that the Fusarium- and A. flavus-inoculated grain produced significantly different volatiles compared to sanitized grain or the positive control. These volatiles changes affected close-range foraging during an Ethovision assay, with a greater frequency of entering and spending time in a small zone with kernels inoculated with A. flavus compared to other treatments. In the release-recapture assay, MVOCs were found to be attractive to L. serricorne at a long distance in traps. While there was no preference shown among semiochemical stimuli shown in a still-air, four-way olfactometer, methodological limitations prevent robust interpretation from this assay. Finally, we found that L. serricorne readily vectored microbes in the postharvest environment after dispersing to novel food patches, but the amount of microbes imparted decreased with the dispersal period. Overall, our research suggests that MVOCs are important for close- and long-range orientation of L. serricorne during foraging, and that MVOCs may have the potential for inclusion in behaviorally-based tactics.