The Behavioral Response of the Stored Product Insects Rhyzopertha Dominica and Tribolium Castaneum to Moldy Grain Volatiles
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Every year producers lose 10-70% of their commodities to insects in the post-harvest supply chain. Rhyzopertha dominica, or lesser grain borer beetle, and Tribolium castaneum, or red flour beetle, are significant primary and secondary stored product pests, respectively. Sanitation and the interception of pests before infestation occurs is vital in the integrated pest management for food facilities. Globally, stored product pests are becoming resistant to traditional fumigants, but the use of attract-and-kill devices could be an effective alternative method of prevention. Fungal volatiles from moldy or off-odor grain may be well-suited to be stimuli in attract-and-kill devices, due to stored product pests having an innate attraction to these compounds, and their uniqueness in grain storage habitats. Our objectives were 1) to study the behavioral responses of R. dominica and T. castaneum to moldy grain volatiles using wind tunnel and release-recapture assays, and 2) to determine the volatiles being released by moldy grain batches that have been tempered with deionized water to 12%, 15%, and 19% moisture content and incubated at 9, 18, 27d intervals. Tempering the grain successfully induced fungal damage in kernels, which resulted in significant changes in the volatiles being emitted. Overall, our study found that R. dominica exhibited attraction to moderately moldy samples in the wind tunnel, whereas T. castaneum were unaffected by the presence of fungal volatiles. Our research highlights the importance of fungal volatiles in the interactions of stored product insects with grain, and suggest they may be useful for future management tactics.