Cold exposure restricts Rhyzopertha dominica F. (Coleoptera: Bostrichidae) population growth across host grains and exposure durations

Authors: CHRISTENSEN, DAWSON - Kansas State University; PARK, YOONSEONG - Kansas State University; Rusch, Travis; Scully, Erin; Gerken, Alison

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2026
Publication Date: 6/1/2026
Citation: Christensen, D., Park, Y., Rusch, T.W., Scully, E.D., Gerken, A.R. 2026. Cold exposure restricts Rhyzopertha dominica F. (Coleoptera: Bostrichidae) population growth across host grains and exposure durations. Journal of Stored Products Research. Vol119;103103. https://doi.org/10.1016/j.jspr.2026.103103.
DOI: https://doi.org/10.1016/j.jspr.2026.103103

Interpretive Summary: The lesser grain borer is a destructive stored product pest that threatens global grain supplies, but new research shows that its survival depends heavily on a combination of storage temperature and the type of grain it infests. By testing the beetles on four different grain commodities (wheat, rice, sorghum, and corn) across various temperatures, wheat was identified as the most vulnerable to infestation and cold temperatures of 5°C were highly effective at stopping population growth across all grain types. In contrast, corn was the least susceptible to feeding damage. Interestingly, while the insect populations thrive at 30°C on all commodities, their numbers declined at 18°C, and the study even developed a predictive model to help grain managers forecast insect populations based on their specific storage temperatures. Ultimately, this means grain managers can use precise cold recipes tailored to each grain to kill common stored product insects like lesser grain borers more efficiently, reducing the need for insecticides.

Technical Abstract: Stored product insects present a major threat to global food security, with the lesser grain borer, Rhyzopertha dominica, among the most destructive pests. Cold temperature treatments can reduce R. dominica survival and reproduction, but insufficient cooling during storage may allow persistence, and survival may vary by commodity. In this study, we quantified total adult R. dominica populations from corn, sorghum, rice, and wheat after storage for 2, 4, 8, or 12 weeks at 5, 18, or 30 °C. Furthermore, two population growth models based on initial adult counts were developed to predict population sizes across treatments and provide managers with a tool to forecast dynamics. Overall, R. dominica counts were highest on wheat, with rice and sorghum supporting more adults than corn across all weeks at 18 and 30 °C, and at week 2 for 5 °C. However, with prolonged exposure to 5 and 18 °C, differences among commodities diminished. At 5 °C, storage beyond 4 weeks did not result in further population decline, whereas populations continued to decrease at 18 °C and increased at 30 °C. Additionally, a model that used grain type and temperature to predict population levels over time performed well, but tended to overpredict population levels at 5 °C, whereas the model using predicted temperatures and observed weeks performed poorly. These results suggest that temperature and exposure duration needed to reduce R. dominica populations vary by commodity, providing practical limits for cold storage conditions and offering a cost- and time-efficient strategy to reduce population growth.