Attraction, mobility, and preference by Lasioderma serricorne (F.) (Coleoptera: Ptinidae) to microbially-mediated volatile emissions by two species of fungi in stored grain

Authors: PONCE, MARCO - Kansas State University; SIERRA, PETRA - Kalamazoo College; JACQUELINE, MAILLE - Kansas State University; KIM, TANIA - Kansas State University; Scully, Erin; Morrison, William - Rob

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2023
Publication Date: 4/15/2023
Citation: Ponce, M.A., Sierra, P., Jacqueline, M., Kim, T.N., Scully, E.D., Morrison III, W.R. 2023. Attraction, mobility, and preference by Lasioderma serricorne (F.) (Coleoptera: Ptinidae) to microbially-mediated volatile emissions by two species of fungi in stored grain. Scientific Reports. 13(1). Article 6176. https://doi.org/10.1038/s41598-023-32973-y.
DOI: https://doi.org/10.1038/s41598-023-32973-y

Interpretive Summary: The cigarette beetle is a cosmopolitan and widespread pest of processing food facilities that attacks raw grains after they have become physically damaged as well as high-value finished commodities. Microbes also contaminate and damage raw grain and can create suitable conditions for insect colonization. Although this insect regularly encounters microbes in environments where it feeds, there is a limited amount of information about whether volatiles from grains that have been colonized by these microbes can attract these insects or alter their behavior. Enhanced knowledge about attraction to microbially-produced odors may be useful for developing tactics to manipulate behavior and manage insect populations. In this study, the behavioral responses of cigarette beetle were characterized to volatiles produced by two different fungi that were isolated from the cuticles of adults. One was identified as Aspergillus flavus and the second was identified as Fusarium spp. When inoculated into grain, these two fungi produced unique volatiles compared to uninoculated grain. In addition, in behavioral experiments, adult cigarette beetles spent more time in zones containing grain inoculated with A. flavus and entered these areas more frequently compared to other treatments, suggesting the microbes produce volatiles that are attractive over short-ranges. Grain inoculated with A. flavus was also attractive when used as baits for traps, indicating long-range attraction. This study suggests that microbial odors are attractive to cigarette beetles over a range of distances and could be used to develop unique attractants for traps to monitor for infestations or baits lure them away from raw commodities by presenting them with unique and/or more attractive volatiles.

Technical Abstract: Little research has linked how specific fungal species affect the behavior of the secondary 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 two fungal morphotypes, 2) characterize the volatile emissions from grain inoculated by each fungal morphotype (A. flavus or Fusarium spp.) compared to unmanipulated and sanitized grain, and 3) understand how MVOCs from each 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. Changes in MVOC emissions 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 longer distances in commercial pitfall traps. While there was no preference shown among semiochemical stimuli in a still-air, four-way olfactometer, it is possible that methodological limitations prevented robust interpretation from this assay. Overall, our study 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 for this species.