Strategy Aiming Insect Pest Control: Anthonomus grandis Transcriptome and Functional Evaluation of Candidate Genes Using RNA Interference

Several species of insect pests attack cotton plants (Gossipium spp). The cotton boll weevil (Anthonomus grandis) (CBW) is the main pest in Brazil and must be controlled to avert economic losses. Among the different strategies used to control insect pests, a strategy involving gene silencing using RNAi is of great relevance. The main advantage of gene silencing technology is the specificity of the effects obtained. We generated a library containing genes expressed by CBW via complete sequencing of ESTs derived from different stages of its development. The transcriptome of CBW generated nearly 500,000 reads and one database with 20,841 contigs. After sequence annotation, candidate genes were selected for validation by silencing via RNAi. The molecules encoded by selected genes are involved in vital biological processes of insects, including digestion, metamorphosis, development, and reproduction. Thirty selected genes were chosen. For validation, we analyzed changes in biological characteristics and altered gene relative expression levels, after microinjection of dsRNAs in larvae and adults. Some of the selected genes showed high potential for controlling the CBW. It was observed that in all cases some stage of insect development was affected and the relative expression of their transcripts was highly reduced. Due to the strong indication of the biotechnological potential, vectors for expression of dsRNA of these genes in plants have been constructed in order to evaluate the silencing. The results are of great importance for generation of cotton plants showing resistance against CBW.

 Supported by CNPq, Capes, Embrapa