Attraction and preference of a cosmopolitan stored product insect to unique microbially-mediated volatile emissions by fungi in grain

Microbes are one of the most dominant organizations on the planet. In particular, interactions between microbes and insects are important for a range of taxa, with emissions by microbes used for mating, foraging, and dispersal by insects. Although some research has investigated the interactions among stored product insects and microbes, very little research has examined how specific fungal species affect the behavior of Sitophilus oryzae. Additional knowledge about attraction to microbially-produced volatile organic compounds (MVOCs) may be used in integrated pest management tactics to manipulate insect behavior. Our goals were to 1) isolate, culture, and identify two fungal morphotypes, 2) characterize the volatile emissions from grain inoculated by each fungal morphotypes, and 3) understand how MVOCs from each fungal morphotype affects foraging, attraction, and preference by S. oryzae. We hypothesize that the headspace blends will be unique among our treatments, and that this will lead to differences in preference and mobility by S. oryzae. To accomplish this, we collected headspace to identify the compounds emitted from two fungal morphotypes, then sequenced each morphotype to make species identifications. Next, we assessed the behavioral response of S. oryzae through the use of a 4-way still-air olfactometer, and video-tracking coupled with Ethovision Software. We found that each morphotype corresponded to Aspergillus flavus and Fusarium spp., with the MVOCs emitted by each considered unique, and that S. oryzae preference and mobility was significantly modulated by these MVOCs. Overall, our research suggests that MVOCs may have potential for inclusion in behaviorally-based tactics.