Evaluating the combination of a parasitoid and a predator for biological control of seed beetles (Chrysomelidae: Bruchinae) in stored beans

The two seed beetle species Acanthoscelides obtectus and Callosobruchus maculatus are among the economically most important pests of stored legume seeds world-wide. Insect natural enemies for biological control were considered in IPM strategies to control bean weevils in store. In this contribution, the control effect by a combination of the parasitoid Anisopteromalus calandrae and the predator Xylocoris flavipes on both seed beetle species was evaluated in a laboratory study on black eyed beans Vigna unguiculata. The combination of parasitoid and predator was most effective against both species of seed beetles. However, in C. maculatus the combination was not significantly more effective compared to A. calandrae alone, suggesting a poor effect on adults and no effect on eggs and larvae by X. flavipes. In the case of A. obtectus, the suppressive effect by the combination of the parasitoid and the predator was high. For C. maculatus, germination of black eyed beans was approximately three times higher when both natural enemies were present. The combination of A. calandrae and X. flavipes is considered a promising component for integrated control of A. obtectus.