A gut transcriptome of the Hessian fly (Mayetiola destructor), a member of gall midges

The Hessian fly is a serious pest of wheat and an experimental organism for the study of gall midge-plant interactions. In addition to food digestion and detoxification, the gut of Hessian fly larvae is also an important interface for insect-host interactions. Analysis of the genes expressed in the Hessian fly larval gut will enhance our understanding of the overall gut physiology and may also lead to the identification of critical molecules for Hessian fly – host plant interactions. Over 10,000 Expressed Sequence Tags (ESTs) were generated and assembled into 2,007 clusters (contigs and singletons). The most striking feature of the Hessian fly larval transcriptome is the existence of a large number of transcripts coding for so-called small secretory proteins (SSP) with amino acids less than 250. Eleven of the 30 largest clusters were SSP transcripts with the largest cluster containing 11.3% of total ESTs. Micorarray and qPCR analyses of representative SSP transcripts revealed that most of them were predominantly present in the gut tissue and the transcript levels of many SSP were affected by plant types on which larvae feed. This study represents the first global analysis of gut transcripts from a gall midge.