Gall midges (hessian flies) as plant pathogens

Authors: STUART, JEFFREY - Purdue University; Chen, Ming-Shun; HARRIS, MARION - North Dakota State University; Shukle, Richard

Submitted to: Annual Review of Phytopathology
Publication Type: Review Article
Publication Acceptance Date: 1/25/2012
Publication Date: 5/29/2012
Citation: Stuart, J.J., Chen, M., Harris, M.O., Shukle, R.H. 2012. Gall midges (hessian flies) as plant pathogens. Annual Review of Phytopathology. 50:17.1-17.19.

Interpretive Summary: The Hessian fly is a major insect pest of wheat. Hessian fly is also a representative of a large group of pests, the gall midges. In many respects, Hessian fly and other gall midges are like biotrophic pathogens. Hessian fly interacts with wheat in a typical gene-for-gene manner, has a fixed feeding site, and manipulates host plants extensively. This review paper summarizes recent advances in research on the Hessian fly – wheat interaction.

Technical Abstract: Gall midges constitute an important group of plant-parasitic insects. The Hessian fly (HF, Mayetiola destructor), the most investigated gall midge, was the first insect hypothesized to have a gene-for-gene interaction with its host plant, wheat (Triticum spp.). Recent investigations support that hypothesis. The minute larval mandibles appear to act in a manner that is analogous to nematode stylets and the haustoria of filamentous plant pathogens. Putative effector proteins are encoded by hundreds of genes and expressed in the HF larval salivary gland. Cultivar specific resistance genes mediate a highly localized hypersensitive reaction that kills avirulent HF larvae. Fine-scale mapping of HF avirulence genes provides further evidence of effector-triggered immunity against HF in wheat. Taken together, these discoveries suggest that the HF, and other gall midges, may be considered biotrophic, or hemibiotrophic, plant pathogens. They demonstrate the capacity the wheat-HF interaction offers to the study of insect-induced gall formation.