Evaluating a push-pull tactic for management of Epilachna varivestis Mulsant and enhancement of beneficial arthropods in Phaseolus lunatus L.

Abstract

Restoring ecological services in agroecosystems can compensate for the negative effects associated with agricultural intensification. For example, disruption of natural pest suppression can be mitigated through habitat manipulation to attract beneficial arthropods and alter colonization by herbivores. We evaluated a push-pull habitat manipulation system for its potential to suppress Mexican bean beetle (Epilachna varivestis Mulsant) and augment natural enemies in lima bean (Phaseolus lunatus L.). The push-pull treatment consisted of P. lunatus interplanted with French marigold (Tagetes patula L.) and bordered by wax snap beans (P. vulgaris L.), and was compared with a P. lunatus monoculture. Greater numbers of E. varivestis and other herbivores were found in the push-pull border (P. vulgaris) relative to the monoculture border and interior rows of both habitat types. Abundances of chewing and piercing-sucking predators were greatest in the interior rows of the push-pull treatment, and parasitoids were more abundant in the interior compared to the border rows of the push-pull treatment. However, while Pediobius spp. parasitoid wasps [Pediobius foveolatus (Crawford) attacks immature stages of E. varivestis] were also more abundant in the push-pull than monoculture treatment, their abundance was higher in the border relative to interior rows. Phaseolus lunatus plant productivity was lower in push-pull compared to monoculture habitats. Although further refinement is necessary, this push-pull strategy shows promise for manipulating Phaseolus cropping systems to improve natural pest control.