A landscape genetics approach to Hessian fly distributions

Hessian fly, Mayetiola destructor (Say), is a wheat crop pest in the United States creating millions of dollars of crop losses each year. The primary means of controlling this insect pest is through the use of resistant cultivars. Over the years, this practice has led to Hessian flies containing genes for virulence. Additionally, other characteristics about Mayetiola destructor biology are likely to reduce gene flow between populations, such as limited dispersal, short life span, and rapid mating and oviposition; however, virulence genes continue to emerge and spread. Knowledge of genetic variation within and between populations is important for monitoring the effects of any insect targeted control strategy, including the spread of virulence to deployed resistance genes in wheat, yet interactions on the population level for this insect remains poorly understood. In order to better understand Hessian fly on the population level, 14 microsatellite markers were used to identify the population structure of 12 Hessian fly collections from the Southeastern United States. A high level of gene diversity and regional gene flow was found. However, geographic distance alone does not explain the genetic distance and structure observed in these collections. Geographic information systems (GIS) software was utilized to aid in identifying what is driving the underlying patterns of genetic variation and structure of the Hessian fly. Possible explanations of Hessian fly structure are explored at length.