EFFECTIVENESS OF DEPLOYING SINGLE GENE RESISTANCES IN WHEAT FOR CONTROLLING DAMAGE BY THE HESSIAN FLY (DIPTERA, CECIDOMYIIDAE)

Discussions and simulation models have been used by others to develop strategies for deploying genes in wheat (Triticum spp.) for resistance to the Hessian fly, Mayetiola destructor (Say). Effects of deploying genes one at a time in sequence and redeploying a gene after a 10-yr absence from the commercial crop in Indiana during 1955-1989 are presented. Three genes, H3, H6, and H5, were deployed in 1955, 1962, and 1971, respectively, and H6 was redeployed in 1981. A reduction in infestation levels of Hessian fly occurred for 6-8 yr after each deployment. Redeployment of H6, after a 10-yr absence in commercial use, was highly effective. Other methods of deploying resistance genes in conjunction with cultural practices should be considered for control of Hessian fly. When considering the pyramiding of genes for resistance, one must evaluate the time required to develop new productive cultivars. Efficient methods to determine that all of the pyramided genes are present in a line are important for the successful use of pyramided genes. Wheat cultivars are seldom grown for more than 8-10 yr, but the same pyramided genes might be used in subsequent cultivars.