AZabrotes subfasciatus‐resistantvariety ofPhaseolus vulgaris(RAZ 2) developed at CIAT in Colombia was compared with local susceptible varieties from Colombia and Uganda using strains of insect from both locations. Two bioassay methods were used to measure relevant parameters. RAZ 2 proved highly resistant to both insect strains. The response of both strains to the resistant cultivar was consistent with the mechanism proposed for the action of the antimetabolite, arcelin 1. Inter‐strain differences and disparity in results from the two bioassay methods were detected and their significance is discussed. ClAT's Z.subfasciatus‐resistant varieties have the potential to markedly reduce losses caused by this pest to beans in tropical farm storage.