Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2013
Publication Date: 3/27/2013
Citation: Morton, P.K., Schemerhorn, B.J. 2013. Population structure and the colonization route of one of the oldest North American invasive insects: Stories from the worn road of the Hessian Fly, Mayetiola destructor (Say). PLoS One. 8(3): e59833. DOI:10.1371/journal.pone.0059833. Interpretive Summary: Hessian fly samples from across the world were sampled and tested to determine the size of the populations, and the relatedness between the populations. We also evaluated whether or not there was, as history indicates, a single introduction of Hessian fly into North America by Hessian soldiers. Using microsatellite markers, we found no evidence of a single introduction and the North American samples of Hessian fly were not like any assessed population from the Old World (Europe, Africa, and Asia). We also discovered evidence of selection pressures on Hessian fly populations in the United States, likely due to cultural practices and the use of resistance genes in the wheat host.
Technical Abstract: We compared levels of genetic diversity and population structure of North American, European, North African, Western Asian, and New Zealand populations of Hessian fly, a wheat pest. The goals of this study were evaluate the evidence of a possible single introduction and westward expansion of Hessian fly into North American and the population genetic structure of current populations. Furthermore, Old World populations were evaluated as possible sources of introduction. We tested diversity and population structure by examining 18 microsatellite loci with coverage across all four Hessian fly chromosomes. Neither genetic diversity nor population genetic structure provided evidence of a westward movement from a single introduction in North America. Introduced populations in North America did not show identity or assignment to any Old World population, likely indicating a multiple introduction scenario with subsequent gene flow between populations. Diversity and selection were assessed on a chromosomal level, and while there were no differences in diversity or selection between chromosomes or between native and introduced populations, there were a great number of candidate loci for both positive and balancing selection from North America.