John Reese and Ming-Shun Chen, Department of Entomology

The goal of this project is to determine the molecular mechanism of insect biotype differentiation using Hessian fly (Mayetiola destructor) as a model system. The proposed research is to test the hypothesis that the proteins secreted into host plants through insect salivary glands are the molecular determinants of different insect biotypes. The hypothesis is based on the observation that, in many plant-pathogen systems, specific virulence/avirulence linked with different races (a concept similar to insect biotypes) of a pathogen is determined by proteins secreted into host plants from the pathogen. From a comprehensive analysis of cDNAs derived from dissected salivary glands with different biotypes and geographic populations, we identified ~2,000 unique genes that encode Secretory Salivary Gland Proteins (SSGPs) from Hessian fly larvae. The proposed research is to: 1) Demonstrate the feasibility of using specially designed microarrays to detect expression differences of the SSGP genes between different biotypes; and 2) Demonstrate the feasibility of using tile-microarrays to detect genetic mutations that may be responsible for biotype differentiation. The occurrence of new insect biotypes is the major challenge for pest management using host plant resistance. The success of this project not only provides useful information for Hessian fly long-term management, one of the most destructive pests of wheat world-wide, but also provides a model system for similar research with other important insect pests.