Combining host plant resistance and botanical insecticide for the management of Zabrotes subfasciatus (Boheman) (Coleoptera, Chrysomelidae, Bruchinae) in common bean

The Mexican bean weevil Zabrotes subfasciatus (Boheman) (Coleoptera, Chrysomelidae, Bruchinae) has become one of the main pests of common bean (Phaseolus vulgaris L.) (Fabaceae) worldwide. The association of resistant bean varieties with botanical insecticides has a great potential for controlling the pest, but it has been little studied so far. Therefore, the present study aimed at selecting a botanical insecticide and evaluating its combined effect with an arcelin-bearing common bean resistant genotype against Z. subfasciatus. We evaluated three botanical insecticides, the rotenone-based Roteline (R) and the neem-based NeemSeto (R) and NeemPro (R), on the development of the insect. NeemPro (R) was the most effective, presenting ovicidal effect and prolonging egg-to-adult period, being selected for the following bioassay. Then we evaluated the effect of NeemPro (R) combined with the resistant common bean genotype IAC 818 (RAZ-59) on some biological parameters of the pest. The most severe effects onZ. subfasciatus were caused by the resistant genotype. However, significant effects in some parameters of the pest were also verified for the botanical insecticide and for its combination with this resistance type/trait in the conditions of the experiment.