D3401: Exploring the population structure of plum curculio (Conotrachelus nenuphar), a native fruit pest in North America

Herbivorous insect populations can exhibit genetic differentiation as a result of local adaptation to their plant hosts, with reproductive isolation resulting in further genetic divergence. Here we investigate the population genetic structure of the native North American orchard pest, Plum curculio (Conotrachelus nenuphar), which exhibits distinct biological differences (preference and performance) when characterized from different host plants. We tested the hypothesis that genetic differentiation among natural populations may develop in an orchard pest with local host adaptation as well as isolation by geographic location. Haplotype diversity and genetic structure were assessed among populations from three plant hosts; apple (pome fruit, tree), peach (stone fruit, tree), and blueberry (berry, shrub) across NJ, in addition to 14 localities (Florida through Massachusetts) covering much of its mid-atlantic range. Minimum spanning haplotype analyses based on mitochondrial DNA indicated strong genetic differentiation between populations representing distinct geographical regions (northeastern and southeastern North America). The results of this work validate the presence of southern haplotypes of C. nenuphar throughout New Jersey and as far north as New York state. In this study, we did not observe genetic differentiation that could be attributed to isolation by ecology, i.e. plant host-associated populations that were collected from the same region. Our results indicate that geographical distance and perhaps barriers are impactful on the genetic structure of Plum curculio, and when attempting to expand our understanding of adaptive host shifts observed for this pest in future work we must take a combination of ecological factors into account.