Walking while dying: preserved behavioral traits during Beauveria bassiana infection of the maize weevil (Sitophilus zeamais)

Entomopathogenic fungi are increasingly regarded as promising alternatives to conventional insecticides for the management of stored-product pests. Their effectiveness, however, depends not only on their ability to kill insect hosts but also on how infection influences behaviors that may affect fungal dissemination and, ultimately, biological control performance. We compared the virulence of six Ecuadorian isolates of Beauveria bassiana against the maize weevil, Sitophilus zeamais , and investigated the behavioral changes elicited by the most virulent isolate at three conidial concentrations (10 7 , 10 8 , and 10 9 conidia mL −1 ). Adult survival was analyzed using Kaplan–Meier survival analysis, whereas repellency, locomotion, and group interaction patterns were quantified using AI-assisted automated video tracking. Isolate BBAL31 exhibited the greatest virulence, causing the most rapid mortality among the isolates evaluated. Repellency varied with conidial concentration, with early avoidance observed at 10 7 conidia mL −1 , whereas at the highest concentration (10 9 conidia mL −1 ) avoidance was delayed, becoming evident only after 36 h of exposure. Despite its high virulence, BBAL31 caused only minor changes in locomotion, including walking distance, speed, resting time, and interaction network density. In contrast, deltamethrin markedly disrupted insect activity, increasing trajectory tortuosity and inactivity while reducing group connectivity. Together, these findings demonstrate that behavioral traits provide complementary insight into the performance of entomopathogenic fungi as biological control agents against stored-product insect pests.