RNAi gene knockdown in the poultry red mite, Dermanyssus gallinae (De Geer 1778), a tool for functional genomics

Abstract

BackgroundThe avian haematophagous ectoparasite, Dermanyssus gallinae or the poultry red mite, causes significant economic losses to the egg laying industry worldwide and also represents a significant welfare threat. Current acaricide-based controls are unsustainable due to the mites ability to rapidly develop resistance, thus developing a novel sustainable means of control for D. gallinae is a priority. RNA interference (RNAi) mediated gene silencing is a valuable tool for studying gene function in non-model organisms, but is also emerging as a novel tool for parasite control. MethodsHere we use an in silico approach to identify core RNAi pathway genes in the recently sequenced D. gallinae genome. In addition we utilise an in vitro feeding device to deliver dsRNA to D. gallinae targeting the D. gallinae vATPase subunit A (Dg vATPase A) gene and monitor gene knockdown using quantitive PCR (qPCR). ResultsWe identified core components of the small interfering RNA (siRNA) and micro RNA (miRNA) pathways in D. gallinae, which indicate these gene silencing pathways are likely functional. Strikingly, the Piwi-interacting RNA (piRNA) pathway was absent in D. gallinae. In addition, we demonstrate that feeding Dg vATPase A dsRNA to adult female D. gallinae results in silencing of the targeted gene compared to control mites fed non-specific lacZ dsRNA. In D. gallinae, dsRNA mediated gene knockdown is rapid, detectable 24 hours after oral delivery of dsRNA and persisted for at least 120 hours. ConclusionsThis study has shown the presence of core RNAi machinery components in the D. gallinae genome. In addition, we have developed a robust RNAi methodology for targeting genes in D. gallinae, which will be of value for studying genes of unknown function and validating potential control targets in D. gallinae.