ABSTRACT

Among insect pests, some systems have been used repeatedly as pesticide targets. The field of genomics however, gives us a new tool in the development of previously untapped targets for pesticide action. The digestive system has been proposed as a likely organ of choice for identification of new pesticide targets (Wang and Granados, 2001). This is partly because the food source can be genetically engineered to produce the pesticide and therefore to deliver it to the insect through feeding. In order to take advantage of the pesticide development tools genomics can provide and to effectively target a species, knowledge of gene expression in the digestive tract of pest organisms is needed. In this project, 957 new expressed sequence tags (ESTs) were randomly sequenced from a cDNA library isolated from the digestive system of the cabbage looper, Trichoplusia ni (Lepidoptera: Noctuidae). Bioinformatics tools were used to assign putative functions to these sequences. Twelve percent of the ESTs were digestive proteins, 9% were ribosomal proteins, 7% matched previously sequenced genes of unknown function, and interestingly, 29% were novel proteins that did not match any published sequence. Over 29% of the sequences matched lepidopteran sequences with 21% matching noctuid genera and 2% specifically matching T. ni. The elongation factor 1 alpha (EF1a) gene, which is necessary for protein translation, was studied further. Bioinformatics analysis of the EF1a-like ESTs indicated that this group actually consists of two genes; the well-studied EF1a and an translation releasing factor, RF3, not previously sequenced in this species. The T. ni sequence database offers researchers the chance to explore specific genes present within this insect and examine new potential insecticide targets.