Resistance of Common Bean (Phaseolus vulgaris L.) Varieties to Bruchid Infestation in Burundi

Abstract

Common beans (Phaseolus vulgaris L.) are essential for global food and nutritional security, but post-harvest losses caused by bruchid beetles (Acanthoscelides obtectus (Say)) and Zabrotes subfasciatus (Boheman)) significantly reduce seed quality and quantity, undermining livelihoods and incomes. This study aimed to evaluate the preference and damage of selected bean varieties to bruchid infestation under controlled and non-controlled storage conditions in Burundi. Experiments were conducted using four common bean varieties Kinure, Mukungugu, Musore, and Gasilida across three sites: ISABU Bujumbura, ISABU Murongwe, and ISABU Kayanza, with 72 treatments on all conditions. In the controlled environment, adult bruchids were introduced directly into sealed experimental jars; in the non-controlled environment, insects were allowed to infest seeds freely from the surrounding environment. A completely randomized design with three replications was used. Before storage, baseline measurements including seed moisture content and seed weight (1,000 g per lot) were recorded. Data were collected on three time points, including counts of live and dead bruchids, seed damage rates, weight loss. Results showed that Kinure consistently exhibited the highest resistance across all storage environments, with over 90% unperforated seeds and minimal weight loss, while Gasilida was the most preferred by bruchids. At ISABU Murongwe and ISABU Kayanza, Kinure maintained unperforated seed rates above 90%, whereas Gasilida recorded up to 57.7% perforation. A. obtectus caused less damage than Z. subfasciatus, and bruchid survival ranged from 60% to 79%. Overall, Kinure and Mukungugu performed best under both storage conditions, highlighting their potential for mitigating post-harvest losses in smallholder farming systems.