Resistance of selected bean genotypes against the seed beetle, Callosobruchus maculatus (Coleoptera: Chrysomelidae) in storage

An experiment was conducted to screen three new P. vulgaris genotypes, CAL96, DAB520 and X-genotype, for resistance against Callosobruchus maculatus, seed beetle in storage at the Botswana University of Agriculture and Natural Resources. Blackeye cowpea was used as a control in the experiment. The experiment was arranged in a Complete Randomized Design (CRD) replicated four times. The seeds were evaluated on the basis of number of eggs laid, adult emergence, adult mortalities, seed weight loss and Dobie Susceptibility Index (DSI). The study revealed that CAL96, DAB520, X-genotype had negative effects on C. maculatus for all parameters measured whilst black cowpeas landrace (control) supported C. maculatus oviposition and adult emergence. CAL96, DAB520 and X-genotype also had an average seed weight loss ranging from of 1%, to 2%, and based on the Dobie Susceptibility Index. CAL96, DAB520 and X-genotype recorded a Dobie Susceptibility Index value of 0% which suggests they are resistant compared with the control which recorded an index value of 8.3% making it susceptible. Therefore, CAL96, DAB520 and X-genotype can be used to achieve effective control of C. maculatus and reduce damage to beans on in storage. They should, therefore, be included in pest management strategies for C. maculatus in grain storages in Botswana.