Bean Landrace Resistance to the Bean Weevil (Acanthoscelides obtectus): A Sustainable Approach to Post-Harvest Pest Management

Bean weevil, Acanthoscelides obtectus, is a major post-harvest pest causing substantial losses in Phaseolus species worldwide. Identifying genetic resources with reduced susceptibility offers a sustainable alternative to chemical control. In this study, four Phaseolus coccineus and nine Phaseolus vulgaris landraces, along with one commercial cultivar, were evaluated under laboratory conditions using a free-choice test. Resistance-related traits, including oviposition (eggs per seed), adult emergence (holes per seed), damage incidence, and seed weight loss, were assessed across three replications. Significant genotypic variation was observed for all traits. Several P. vulgaris landraces (APN 42, APN 51, Yar) and one P. coccineus landrace (APN 85) showed no detectable seed damage or seed weight loss under free-choice conditions, whereas the susceptible check exhibited high infestation levels and up to 39.3% seed weight loss. Principal component analysis further distinguished low-damage genotypes from susceptible landraces, with resistance-associated traits contributing strongly to variation. These findings indicate that certain landraces exhibit reduced susceptibility to, or non-preference for, the bean weevil and may serve as valuable genetic resources for sustainable pest management.