Pyrosequencing the Cosmopolites sordidus midgut transcriptome reveals candidate genes for silencing (RNAi)

The intestinal tract of insects has been the main target of many control strategies that use insecticide molecules, many of which have been generated by genetic engineering. A better understanding of the genes that are expressed in the digestive tract of insects and their physiological role, will allow propose new and more effective strategies in order to control insect pests of economic importance. In the present work we characterized the midgut transcriptome of the banana weevil borer, C. sordidus by using massive 454-pyrosequencing. The characterization of the transcriptome of C. sordidus was conducted through the analysis of normalized cDNA that was prepared from mRNA extracted from midgut sections of fourth instar larvae. A total of 596.389 sequences were obtained, which generated 47,729 contigs with an average length of 491 bp. Almost 35% of the contigs were significantly similar to insect-related proteins, and 13.5% of them received an EC number, which assigned a known enzymatic function. Transcriptome analysis also allowed us the identification of genes for Bt toxin receptor proteins, candidate genes for silencing (RNAi), and genes involved in detoxification and digestion of cellulose and other polysaccharides.