Landscape simplification alters insect pollinator and herbivore communities with cascading consequences for wild plant evolution

As natural landscapes are modified by humans and converted into simplified agricultural or urbanized landscapes, the community composition and interactions of organisms persisting in these modified landscapes are inherently altered. Important to agriculture as both mutualists and antagonists, numerous studies have examined how insect interactions with crop systems are affected by landscape simplification. However, few studies have examined how this landscape simplification affects insect interactions with wild plants growing in semi-natural areas along agriculture such as field margins or riparian buffers. These interactions are dictated not only by the composition of insects present in the landscape, but their movement between the crop and natural communities. Here we examine how insect interactions with a common wild brassica species, Barbarea vulgaris, in field margins vary along a gradient of increasing agricultural land cover in the surrounding landscape. We documented insect interactions with both sentinel plants from a single parent genotype and the natural populations at each site to test how insect populations vary with the landscape and whether the local plant populations show evidence of adaptation. We found a decrease in pollinator visitation and herbivore damage in more simplified landscapes for the sentinel plants but not the natural plant populations. This suggests local adaptation in plant populations is compensating for landscape mediated changes in the insect community. This work contributes to our understanding of how the effects of landscape simplification on insect communities can have cascading consequences for evolution in plant populations.