Gene silencing through RNA interference (RNAi) has revolutionized the study of gene function,
particularly in non-model insects. However, in Lepidoptera (moths and butterflies) RNAi has many times
proven to be difficult to achieve. Most of the negative results have been anecdotal and the positive
experiments have not been collected in such a way that they are possible to analyze. In this review, we
have collected detailed data from more than 150 experiments including all to date published and many
unpublished experiments. Despite a large variation in the data, trends that are found are that RNAi is
particularly successful in the family Saturniidae and in genes involved in immunity. On the contrary, gene
expression in epidermal tissues seems to be most difficult to silence. In addition, gene silencing by
feeding dsRNA requires high concentrations for success. Possible causes for the variability of success in
RNAi experiments in Lepidoptera are discussed. The review also points to a need to further investigate the
mechanism of RNAi in lepidopteran insects and its possible connection to the innate immune response.
Our general understanding of RNAi in Lepidoptera will be further aided in the future as our public
database at http://insectacentral.org/RNAi will continue to gather information on RNAi experiments.
2010 Elsevier Ltd. All rights reserved.