Genetic structure and gene flow among Brazilian populations of Heliothis virescens (Lepidoptera: Noctuidae).

Population genetic studies are essential to the better application of pest management strategies, including the monitoring of the evolution of resistance to insecticides and genetically modified plants. Bacillus thuringiensis Berliner (Bt) crops have been instrumental in controlling tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), a pest that has developed resistance to many common insecticides once used for its management. In our study, microsatellite markers were applied to investigate the genetic structure and patterns of gene flow among Brazilian populations of H. virescens from cotton, Gossypium hirsutum L., and soybean, Glycine max (L.) Merr., fields, aiming to propose means to improve its management in the field. In total, 127 alleles were found across nine microsatellites loci for 205 individuals from 12 localities. Low levels of gene flow and moderate to great genetic structure were found for these populations. Host plant association, crop growing season, and geographic origin were not responsible for the genetic structuring among Brazilian populations of H. virescens. Other factors, such as demographic history and seasonal variability of intrapopulation genetic variation, were suggested to be molding the current pattern of genetic variability distribution.