|GORE, JEFFRY - Mississippi State Extension Service|
|JACKSON, RYAN - Syngenta|
Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2014
Publication Date: 1/2/2015
Publication URL: http://handle.nal.usda.gov/10113/60322
Citation: Perera, O.P., Gore, J., Snodgrass, G.L., Jackson, R., Allen, K.C., Abel, C.A., Luttrell, R.G. 2015. Temporal and spatial genetic variability among tarnished plant bug, Lygus lineolaris (Hemiptera: Mididae)population in a small geographic area. Annals of the Entomological Society of America. 1-12 DOI: 10.1093/aesa/sau016.
Interpretive Summary: Five tarnished plant bug populations in an approximately 15 km transect near Stoneville, MS, USA were sampled in May, July, and September of 2006. The samples from the populations were analyzed with 13 polymorphic genetic markers (microsatellites). Statistical genetic analyses indicated that these populations formed two distinct genetic clusters. Early season populations consisted of predominantly genetic cluster 1 insects, while genetic cluster 2 insects were predominant in the populations collected in September. Additional analyses revealed the study populations had been subjected to bottlenecks, possibly due to insecticide sprays and diapause during winter months. Random genetic drift, uneven gene flow, and genetic structure may have played a major role in the genetic differentiation observed in the tarnished plant bug populations.
Technical Abstract: Lygus lineolaris (Palisot de Beauvois) populations were sampled from five locations near Stoneville, MS, USA at three time points in May, July, and September 2006. Genotype data obtained from 1418 insects using 13 microsatellite markers were analyzed using standard methods to obtain population genetic parameters such as inbreeding coefficients, gene flow, and linkage disequilibrium. Analysis of molecular variance (AMOVA), Bayesian analyses, and factorial correspondence analysis (FCA) were carried out to evaluate the tarnished plant bug populations for genetic structure. The total number of alleles per locus across all populations ranged from 9 to 25 and the average allelic richness calculated by rarefaction across all loci ranged from 3.0 to 3.46. The populations also had low Garza-Williamson indices (M values) ranging from 0.283±0.126 to 0.524±0.260, which indicated a population bottleneck. Deviations from Hardy-Weinberg equilibrium (HWE) and linkage disequilibrium at some loci in some populations may have indicated selection at some loci. Bayesian simulations using STRUCTURE software and the FCA analysis indicated the presence of two genetic clusters in all 15 collections and a temporal shift was observed in the proportion of tarnished plant bugs in the two genetic clusters. Collections made in May 2006 had a high proportion of cluster 1 genotypes (except for the collection B1) and those collected in September had a high proportion of cluster 2 genotypes. Statistical genetics analyses indicated significant differences among and between collections made at different time points, especially between the collections with high proportions of cluster 1 genotypes and cluster 2 genotypes. While random genetic drift and gene flow may have contributed to the seasonal variations observed in the study populations, selection by many insecticide sprays applied in 2005-2006 to control tarnished plant bugs on cotton could also have played a significant role in the temporal variation in genetic structure observed in the tarnished plant bug populations.