The chemical communication and monitoring of Sitophilus zeamais is robust to deviations in temperature

Authors: HETHERINGTON, MATTHEW - Kansas State University; ABSHIRE, JENNIFER - Animal And Plant Health Inspection Service (APHIS); Gerken, Alison; Morrison Iii, William

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Facilities where grain is stored and processed are complex and variable environments, with ambient temperature varying considerably between office space, milling floors, and bulk storage bins. Temperature is known to influence the abundance and types of stored product insect pests encountered across these environments, but the degree to which temperature influences stored product insect volatile production and response to pheromone-baited traps used to monitor populations remains unknown. To address this, we characterized volatile emissions from three populations of maize weevil reared at three temperatures (28°C, 32°C, and 36°C) and aged weevil monitoring lures for extended periods under the same temperatures. In comparing the volatile emissions of three different populations of maize weevil under the three different temperatures, we found the volatile profiles were similar across populations and temperatures, as was the emission rate of the lure. This suggests that thermal stress has a limited effect on chemical communication in maize weevil, and under hot environments, maize weevil is expected to be able to emit, perceive, and respond to volatiles as normal. In addition, we found that temperature did not influence emission rates of pheromone lures used for monitoring, although emission rates did decline over time. Nonetheless, trap catches were similar across all time points, indicating that the reduced emission rate did not impact trap efficacy. These findings suggest that traps and lures will be effective for MW under hot environments, and are robust to variation in ambient temperatures, supporting use by end users for effective monitoring.

Technical Abstract: Stored product environments represent highly heterogeneous environments, with ambient temperature varying considerably between office space, milling floors, and bulk storage bins. Temperature is known to influence the assemblage of pests encountered across these environments, but the degree to which temperature influences stored product insect pheromonal communication pathways and semiochemical-based monitoring programs remains unknown. To address this knowledge gap, we compared the volatile emissions of three strains of Sitophilus zeamais reared at 28°C, 32°C, and 36°C. The overall volatile profiles derived from cohorts of 20 mixed-sex individuals were similar across strain and temperature regime, as was the emission rate of the aggregation pheromone, sitophilure ([4S,5R]-5-hydroxy-4-methyl-3-heptanone), suggesting that thermal stress has a limited effect on chemical communication in S. zeamais. Additionally, we examined how incubation at 28°C, 32°C, and 36°C influenced the emission rate of sitophilure from and efficacy of commercial monitoring lures over 14 days. While lures incubated at 36°C emitted sitophilure at 4-fold lower rates than those incubated at 28°C or 32°C after 7 days, lure efficacy was similar across temperature regimes. These findings suggest that both chemical communication and semiochemical-based monitoring of S. zeamais are relatively robust to variation in ambient temperature.