How evidence-based policy can meet the needs of pollinator conservation without compromising the needs of pest management

The North American monarch butterfly (Danaus plexippus) is a candidate species for listing under the Endangered Species Act. Multiple factors are associated with the decline of the eastern population, including loss of breeding and foraging habitat and pesticide use. Establishing habitat in Midwest row crop landscapes is critical to increasing reproduction during the summer. Our group integrated spatially explicit modeling with empirical movement ecology and pesticide toxicology studies to simulate population outcomes for different habitat establishment scenarios. Because of their mobility, we conclude breeding monarchs in the Midwestern states should be resilient to pesticide use and habitat fragmentation. Consequently, we predict adult monarch recruitment can be enhanced even if new habitat is established near pesticide-treated crop fields. Simulated population increases are maximized when integrated pest management practices and spray drift mitigation measures are assumed. Our research has improved understanding of monarch population dynamics at the landscape scale by examining the interactions between monarch movement ecology, habitat fragmentation and pesticide use. These landscape-scale findings may not be applicable to other Midwest pollinators of conservation concern that are generally less mobile than the monarch.  Consequently, their populations are likely less resilient to habitat fragmentation and more vulnerable to extirpation of sub-populations due to pesticide exposure. This research illustrates the need for developing information that can support conservation plans for specific pollinators across space, time and institutions.