Mechanisms of RNA interference

The functioning of dsRNA in a given pest could be influenced by the method used for dsRNA delivery, the expression levels of genes coding for proteins involved in uptake and processing of dsRNA, the levels of dsRNA degrading enzymes, dsRNA transporters and the presence of viruses. To understand the differential functioning of RNA in different insect species, we propose to use four model insects: two beetles, Tribolium castaneum and Leptinotarsa decemlineata in which RNAi works very well and two moths, Heliothis virescens and Spodoptera frugiperda in which RNAi does not work very well. Sequence information and cell lines are available for all of these insects. Comparative studies using cell lines and tissues dissected from these four species will be used to identify genes responsible for the differential functioning of RNAi in these insects. The specific objectives are: 1) Identify and compare expression of dsRNases in beetles and moths, 2) Compare uptake of dsRNA into beetle and moth cell lines and tissues, 3) Identify proteins involved in transport of dsRNA into cells, 4) Identify proteins responsible for differences in efficiency of RNAi in beetles and moths.