Genetic Population Structure of Lygus hesperus in the Texas High Plains

Information on the population genetic diversity of insect pests is essential for understanding variation in their morphological, behavioral or biological characters and predicting various ecological processes in pest populations. Lygus hesperus is the emerging insect pest of cotton in Texas. Information on the genetic diversity of this pest is lacking from the Texas High Plains region. Therefore, a molecular population genetic diversity study was designed to determine the population genetic structure of L. hesperus from this region. L. hesperus samples (n=48) were collected from four different locations, 40 to 65 miles apart, from the Texas High Plains along a North-South altitude gradient. L. hesperus samples were genotyped by polymerase chain reaction (PCR) and poly acrylamide gel electrophoresis (PAGE) using six microsatellite markers developed and characterized previously in our laboratory. This study showed microsatellite markers are very useful molecular tools for study of neutral genetic variation of L. hesperus populations within the Texas High Plains region. L. hesperus populations within a 140-mile geographic range were genetically differentiated into two distinct populations (northern and southern population clusters). We hypothesize that the genetic differentiation might be caused by differences in ecological elements such as varied hosts, different soil types and the north-south altitude gradient (approximately 623 feet). A larger scale landscape-genetics study is planned for determining the relationships between the ecological parameters and the genetic diversity of the L.  hesperus populations in the Texas High Plains.