Short-term cold acclimation influences Rhyzopertha dominica (Coleoptera: Bostrichidae) mobility in different temperatures.

Stored product insects threaten global food security, yet their ecology remains largely understudied. The lesser grain borer, Rhyzopertha dominica F. (Coleoptera: Bostrichidae), is among the most damaging pests of stored grain. Because locomotion underpins resource and mate finding, impaired movement can reduce colonization success. While cold storage is an effective management strategy, insects may counter these measures through adaptive responses, such as acclimating to low temperatures. Changes in seasonal patterns can increase opportunities for acclimation, and misapplied treatments may reduce the efficacy of temperature-based pest control. To examine behavioral effects of acclimation, we quantified walking of R. dominica across 2 strains (lab and wild), sexes, and acclimation treatments (18 °C for 24 h vs no acclimation) at 10, 20, and 30 °C. Distances moved and proportions of immobile and high-mobility events were recorded for 1 h. Movement increased with temperature in all treatments. At 10 °C, acclimated R. dominica moved farther, had fewer immobile events, and more high-mobility events than those in the non-acclimated treatment, whereas at 20 and 30 °C, the patterns reversed. Females and lab strain R. dominica moved more than male and wild strain counterparts in all temperatures, with females showing higher activity at 20 and 30 °C and lab strain only at 30 °C. These results indicate that short-term cold acclimation enhances locomotion at low temperatures while suppressing movement at higher temperatures, with effects further modulated by sex and strain. Furthermore, the findings emphasize the need for careful application and monitoring of cold storage protocols to maintain effective grain protection.