Chitosan and salicylic acid as elicitors on pod formation in common beans (Phaseolus vulgaris) and their post-harvest impact against the Mexican bean weevil Zabrotes subfasciatus.

backgroundCommon bean Phaseolus vulgaris L. (Fabales: Fabaceae) is a major source of dietary protein in Latin America. However, its productivity and postharvest quality are often limited by abiotic stresses and biotic pressures, particularly infestations by the bruchid weevil Zabrotes subfasciatus Boh. (Coleoptera: Chrysomelidae). This study investigates the effects of foliar applications of salicylic acid (SA) and chitosan (Ch) during the pod formation stage on bean resistance to storage damage caused by Z. subfasciatus, as well as their influence on yield, bromatological composition, and secondary metabolite content.

resultsThe application of SA (1.0 mM) and Ch (1.0 and 5.0 μM) significantly enhanced the phenolic compounds of common bean seeds, increasing total flavonoids to up to 5 mg catechin equivalents/g and bound phenolic compounds to up to 40 mg gallic acid equivalents/g. Notable fold changes were observed in key compounds: gallic acid increased by 4.88- and 4.62-fold, 3,4-dihydroxybenzoic acid by 4.62- and 5.22-fold, and quercetin by 14- and 12-fold under 1.0 mM SA and 5.0 μM Ch treatments, respectively. Ch increased insect mortality by 23.5%. Additionally, the 1.0 mM SA and 5.0 μM Ch treatments reduced seed weight loss by 52% and 56%, decreased seed damage by 23% and 43%, and lowered insect emergence by 68% and 64%, respectively, in response to Zabrotes subfasciatus infestation. Importantly, these treatments did not affect the proximate composition of the beans, thereby preserving their nutritional quality.

conclusionOur results demonstrate that eliciting common bean plants with 1 mM SA and 5.0 μM Ch increases flavonoid and bound phenolic content, while significantly reducing Z. subfasciatus emergence, oviposition, and seed damage. © 2026 Society of Chemical Industry.