Pest genetic resources: Leveraging diversity patterns across agricultural landscapes

Invertebrates are economically important when they are a benefit or detriment to human endeavors, especially so with agriculture. Development of genetic resources for pest species enables researchers to distinguish species, strains, and populations, and to elucidate their interactions, affinities, and history. Such demographic information is critical for understating pest population dynamics, invasion routes, responses to climate change, and design of management strategies. Yet there are many major and minor agricultural pests that are poorly characterized demographically and historically. One such case—the plum curculio beetle, Conotrachelus nenuphar—is an economically important native pest in the United States and Canada on apples, peaches, plums, cherries, and other fruits. If left uncontrolled, plum curculio will decimate fruit crops. Conotrachelus nenuphar is also a pest of global concern as it is listed as a quarantine pest by governments and Regional Plant Protection Organizations covering all continents. Plum curculio samples were collected from more than 40 locations across its entire range, quadrupling previous sampling efforts. Specimens were sampled for several molecular loci (mitochondrial and nuclear) and shown to be geographically and genetically highly structured, corroborating and greatly expanding previous findings. An argument for treating this species as a species complex is built around the molecular results, with implications for pest management. Demographic inference of this species history is used as a case study to illustrate the utility of understanding genetic variation across agricultural ecosystems.