Apurba Barman
Major Professor: Dr. Raul Medina
Ph.D. Candidate
"Host Mediated Genetic Differentiation in Cotton Fleahopper."
"Host Mediated Genetic Differentiation in Cotton Fleahopper." Evidence of population level genetic differentiation due to host association in phytophagous insects of agricultural importance is limited mostly to aphids, which reproduce parthenogentically and are relatively immobile. Here we report genetic differentiation in populations of the polyphagous, mobile, and non-parthenogenetic plant bug, cotton fleahopper (Pseudatomoscelis seriatus Hemiptera: Miridae) feeding on different host-plant species. Horsemint (Monarda spp.), cotton (Gossypium hirsutum), and wooly croton (Croton capitatus) are three host plant species with which cotton fleahopper intimately interact at different times of the year. Cotton flea hopper populations collected from these three host-plants in different cotton growing areas of Texas were screened with genetic markers (AFLP, amplified fragment length polymorphism). The genotype screening results were analyzed by the Bayesian method, using STRUCTURE 2.2® software. The observed clustering pattern infers the existence of differentiated genotypes of cotton fleahopper. There is a distinct genotype that corresponds to individuals collected from horsemint plants in west Texas. Behavioral assay results (olfactory response) of the cotton fleahopper associated with horsemint in western Texas were significantly different than the ones obtained from their southeastern counterpart in terms of their preference for horsemint over cotton. Considering these genetic and behavioral differences, it appears that cotton fleahopper populations associated with horsemint in the western part of Texas (Lubbock and San Angelo) are experiencing host associated differentiation. The lower abundance of horsemint, its asynchronous existence with susceptible stages of cotton and the absence of a common winter host (wooly croton) in the western part of Texas may constitute factors promoting this differentiation.