Identification of Lygus bugs with DNA barcoding

A complex of Lygus bugs species that is dominated by Lygus hesperus Knight (Heteroptera: Miridae) is the key direct pest in a broad range of crops in the Western United States. Cropping systems adversely impacted by Lygus feeding include alfalfa seed, conifer nurseries, pulse crops, and strawberries. In order to fully implement Integrated Pest Management tactics in the diversity of agroecosystems it is necessary to accurately identify the pest. Although L. hesperus is the presumed dominant species, there are several other species of Mirids in the west. In addition, there is evidence that substantial differences exist among closely related species in their host plant preference, susceptibilities to insecticides, intensity of parasitism by specific parasitoids, and level of predation from a complex of generalist predatory beneficial insects within and among regional cropping systems. We are using DNA barcoding and population genetic analyses to identify cryptic Lygus species on different crops in California, and alfalfa in Washington, and Idaho. We have sequenced approximately 500 bp of the mitochondrial cytochrome oxidase 1 gene from Lygus from each of these locations. This has provided evidence of haplotype differentiation and phylogenetic relationships of the bugs in this study. These results are the first step in a comprehensive genetic analysis of Lygus bug in the Western United States that will allow us to accurately predict gene flow and species relationships for our future efforts in implementation of IPM strategies.