Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2009
Publication Date: 4/1/2009
Citation: Chen, M., Echegaray, E., Whitworth, J., Wang, H., Sloderbeck, P.E., Knutson, A., Giles, K.L., Royer, T.A. 2009. Virulence Analysis of Hessian Fly (Mayetiola destructor) Populations from Texas, Oklahoma, and Kansas. Journal of Economic Entomology. 102:774-780.
Interpretive Summary: The Hessian fly is a destructive insect pest of wheat. The most effective means to control Hessian fly damage is to develop and deploy wheat varieties that are resistant to the insect. The challenge for the host plant resistance strategy is the dynamic change of Hessian fly biotypes in the field. Specific resistance genes can lose effectiveness due to changes in Hessian fly biotypes. In order for the host plant resistance strategy to be continuously successful, we need to monitor which resistance genes are still effective periodically. This research investigated the effectiveness of 20 known resistance genes to field Hessian fly populations from Texas, Oklahoma, and Kansas. Five of the 20 tested genes, H13, H21, H25, H26, and Hdic, conferred high levels of resistance (> 80% of plants scored resistant) to all tested geographic populations. However, resistance levels for other genes varied depending on which Hessian fly population they were tested against. This study should provide useful information to breeders when they select resistance genes for their breeding programs and to wheat growers when they select wheat varieties for planting.
Technical Abstract: In recent years, the number of wheat fields heavily infested by Hessian fly (Mayetiola destructor) appears on the rise in the South central Great Plains of the U.S. Historically, resistance genes in wheat have been the most efficient means to control the damage caused by this insect pest. To determine which resistance genes are still effective in this area, virulence of six Hessian fly field populations from Texas, Oklahoma, and Kansas was determined by using the resistance genes H3, H4, H5, H6, H7H8, H9, H10, H11, H12, H13, H16, H17, H18, H21, H22, H23, H24, H25, H26, H31, and Hdic. Five of the tested genes, H13, H21, H25, H26, and Hdic, conferred high levels of resistance (> 80% of plants scored resistant) to all tested geographic populations. However, resistance levels for other genes varied depending on which Hessian fly population they were tested against. H22 and H23 provided high levels (>80%) of resistance to the Oklahoma and Texas populations, but were much less effective (<50%) against the Kansas population. The H7H8 gene combination and H9 were highly resistant (>80%) to the Kansas population, but were not very effective against the Oklahoma and Texas populations. Surprisingly, H31, a new gene identified only five years ago and thus probably not deployed in this region yet, provided only modest (50-70%) resistance to the Texas flies. Biotype composition analysis of insects collected directly from wheat fields in Grayson county, Texas, revealed that the proportion of individuals within this population virulent to the major resistance genes was 89% for H6, 58% for H9, 28% for H5, 22% for H26, 15% for H3, 9% for H18, 4% for H21, and 0% for H13. Our results also revealed that the percentages of virulent biotypes against specific resistance genes in a given population are highly correlated (correlation coefficient 0.97) with the percentages of susceptible plants in a virulence test, suggesting that virulence assays, which requires less time and effort, can be used to approximate biotype composition.