Inheritance of host-plant choice in the seed beetle Callosobruchus maculatus (Coleoptera: Bruchidae)

We performed population crosses to estimate the mode of inheritance of both host acceptance (as determined in single-host arenas) and host preference (as determined in paired-host arenas) in the seed beetle Callosobruchus maculatus (F.). Egg-laying females from 2 parental populations differed predictably in their responses to 2 legume hosts. Females from an African strain accepted cowpea, Vigna unguiculata, (a familiar bust) more often than they accepted mung bean. Vigna radiata, (a novel host), and they preferred cowpea when both hosts were available simultaneously. Females From an Asian strain, for which mung bean had been a lang-term host. tended not to distinguish between the 2, hosts or preferred mung bean. Host acceptance by reciprocal F(1) and F(2) hybrids generally suggested dominance toward the Asian strain: like Asian-strain females, hybrids accepted the 2 hosts nearly equally in short-term exposures. and their lifetime fecundities were consistently higher on mung bean than oil cowpea. In contrast, the egg-laying behavior of F(1) hybrids in paired-host arenas indicated additive (intermediate) inheritance of host preference, along with a maternal effect. Inferences regarding the inheritance of oviposition behavior can therefore depend on experimental protocol (i.e., choice or no-choice situations). Both additive inheritance of host preference and dominance toward lower specificity would promote rapid increases in diet breadth in this species.