Genome-wide markers reveal temporal instability of local population genetic structure in the cotton fleahopper, Pseudatomoscelis seriatus (Hemiptera: Miridae).

BACKGROUND: The cotton fleahopper, Pseudatomoscelis seriatus (Reuter) (Hemiptera: Miridae), is a pest of upland cotton, Gossypium hirsutum L. (Malvales: Malvaceae), that attacks pre-floral buds (squares), leading to abscission and yield losses. In the Brazos Valley cotton production area of Texas (USA), P. seriatus exhibits a seasonal pattern of host use. In spring, eggs hatch from stems of the overwintering host, woolly croton, Croton capitatus Michx. (Malpighiales: Euphorbiaceae). During the growing season, individuals feed on a variety of host plants, including cotton. Adults return to woolly croton at season end to oviposit. We investigated if genetic differentiation exists between populations infesting cotton and those infesting alternative hosts, and whether woolly croton serves as a year-end site of admixture that could be suitable as a natural refuge for the purposes of insect resistance management. We combined high-throughput DNA sequencing with fine-scale spatio-temporal sampling to test (i) whether a population genomic approach would recover patterns of genetic variation consistent with earlier studies and (ii) if local genetic population structure was robust to seasonal changes in local habitat over time.
RESULTS: We found high gene flow among populations of P. seriatus collected from different host plants in the Brazos Valley. We also identified temporal instability of the local population genetic structure, including the near complete loss of a genotypic group that had been previously abundant.
CONCLUSION: We support the status of woolly croton as a natural refuge that promotes year-end gene flow between genotypes infesting cotton and those infesting alternative hosts.