Using NextRAD Sequencing to Infer Fine-Scale Movement of Insects

Winged herbivorous insects can readily move between habitats and/or host plants. Analysis of genetic variation has been one tool to understand insect dispersal patterns. Existing approaches have generally been most effective when looking at broad-scale movement patterns, where genetic variation at a relatively coarse scale is informative. Here, we explore the use of Nextera-tagmented reductively-amplified DNA (“NextRAD”) to explore relatively fine-scale movement patterns of the potato psyllid, Bactericera cockerelli. The potato psyllid is of fundamental interest as a polyphagous herbivore that disperses broadly to reach different host-plant species, and is of applied interest as the vector of zebra chip disease of cultivated potato (Solanum tuberosum). We identified 8,443 single nucleotide polymorphism (SNPs) of potato psyllids separated spatiotemporally in potato fields or on a key non-crop overwintering host, bittersweet nightshade (S. dulcumara), across an agricultural landscape. A subset of the potato psyllids on potato exhibited close genetic similarity to insects in nearby nightshade patches, inferring movement of the insects between these two host plants. However, a second subset of potato-collected psyllids was genetically distinct from those collected on nightshade; this suggests that another, currently un-recognized host plant could be contributing to psyllid populations in potato. Altogether, our results provide evidence that NextRAD sequencing is an effective means to delineate complex patterns of insect movement across landscapes. This approach may have broad utility for the many systems where plant or animal pathogens are vectored by small, highly-mobile insects.