Invasion history and adaptation genomics of the Colorado potato beetle (Leptinotarsa decemlineata) using RAD markers

The Colorado potato beetle, Leptinotarsa decemlineataSay (Coleoptera: Chrysamelidae) is one of the most successful insect pests in agriculture. However, its evolutionary origins as an insect pest of potato remain unclear, as different geographic beetle populations vary phenotypically in host plant affinity, cold tolerance, and behavior. From the beetle’s hypothesized origins in the highlands of Mexico, Spanish settlers are thought to have facilitated its geographic range expansion to the Midwestern US, where it expanded its host range onto the potato. Both the development of cold tolerance and host range expansion were major evolutionary transitions that likely have a genetic basis. 

This is a preliminary examination of SNP diversity and population structure of Colorado potato beetle (CPB) using next-generation sequencing (NGS). We used paired-end restriction-site associated DNA sequencing (RAD-seq) to identify SNP markers in 40 samples from nine populations of native and introduced CPB from the US and Mexico. This is the first use of NGS in the study of geographic variation in CPB.

The recent completion by the I5K Insect Genome Sequencing Initiative of a CPB genome will allow the SNPs discovered in this analysis to be used to identify outlier loci that may be genomic signatures of selection due to invasive range expansion and host shifts.