Gene discovery and functional genomics in an invasive tephritid model pest species, the Mediterranean fruit fly, Ceratitis capitata

The medfly is a highly invasive agricultural pest that has become a model insect for the development of biological control programmes. Despite research into the behavior and classical and population genetics of this organism, the quantity of sequence data available is limited. We used an expressed sequence tag (EST) approach to obtain detailed information on transcriptome signatures that relate to a variety of physiological systems in the medfly. Given that the study was based on normalized cDNA libraries from embryos and adult heads we have obtain information relating to reproduction, sex determination, and chemosensory perception. Over 21,000 high-quality ESTs were obtained from the embryo and head libraries. Clustering analyses resulted in almost 12,000 unique sequences or transcripts. These assembled sequences represent a wide range of biological processes and molecular functions. Of particular interest are the sequences that share homology with Drosophila genes involved in sex determination, olfaction, and reproductive behaviour. The sequences obtained in this study represent the first major dataset of expressed genes in a tephritid species of agricultural importance. This resource provides essential information to support the investigation of numerous questions regarding the biology of the medfly and other related species and also constitutes an invaluable tool for the annotation of complete genome sequences. Our study has revealed intriguing findings regarding the transcript regulation of sex determination genes, as well as insights into the comparative genomics of genes implicated in chemosensory reception and reproduction