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)

Abstract

An integral part to understanding the biology of an invasive species is determining its origin, particularly in pest species. As one of the oldest known invasive species, the goals of this study were to evaluate the evidence of a westward expansion of Hessian fly into North America, from a potential singular introduction event, and the population genetic structure of current populations. Levels of genetic diversity and population structure in the Hessian fly were compared across North America, Europe, North Africa, Western Asia, and New Zealand. 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, with no differences in diversity or selection between chromosomes or between native and introduced populations.

Differential expression of candidate salivary effector proteins in field collections of Hessian fly, Mayetiola destructor

“…In the current study, SSGP transcript abundance in the six field collections fell into three geographical groups based on similarity of SSGP expression and wheat class grown in the geographical region: (1) southeastern USA; (2) central USA; and (3) the Middle East. These groupings were also in agreement with a previously published population survey that revealed the worldwide structure of Hessian fly populations using microsatellite markers (Morton & Schemerhorn, 2013 ). Alabama and Georgia are located in the southeastern USA, where soft-red-winter wheat varieties are grown, and multiple R genes ( H 3, H 5, H 6, H 7 H 8, H 9 and H 13) have been deployed in adapted wheat varieties (Cambron et al ., 2010 ).…”

“…Thus, the variations in expression documented are not because of different wheat genotypes. Therefore, the documented variation in expression of SSGP genes is associated with genetic adaptations that accumulated over time from environmental and agro-ecosystem selection pressures (Morton et al ., 2011 ; Morton & Schemerhorn, 2013 ). These selection pressures could influence population structure and evolution in the field and influence the expression of effectors.…”

“…To date, no data are available on the expression of SSGP transcripts in field collections from different geographical regions. There is population data using microsatellite markers that document the structure of Hessian fly populations (Morton et al ., 2011 ; Morton & Schemerhorn, 2013 ). Therefore, the focus of the present study was to compare transcript abundance from four previously studied SSGP families in Hessian fly from different geographical regions (Liu et al ., 2004 ; Chen et al ., 2008 , 2010 ).…”

Quantitative Trait Locus Analysis of Hessian Fly Resistance in Soft Red Winter Wheat

“…Microsatellite data [ 15 ] and virulence assays [ 13 ] indicated that there is just one major population of HF in the SE US with population structure as well as microscale diversity [ 13 , 15 ]. HF populations from Holmes County, Mississippi, and Florence County, South Carolina, had a different population identity when compared to populations from other counties from SE states [ 16 ]. The H12 , H13 , H18 , H24 – H26 , H31 – H33 , and Hdic genes are still effective in multiple SE counties, but H24 – H26 can be associated with undesirable agronomic traits [ 14 ].…”