BACKGROUND: Aethina tumida is a serious pest of the European honey bee (Apis 
mellifera) in North America and Australia. Here we investigate whether Laccase 
2, the phenoloxidase gene essential for cuticle sclerotisation and pigmentation 
in many insects, and vacuolar-ATPase V-type subunit A, vital for the generation 
of proton gradients used to drive a range of transport processes, could be 
potential targets for RNAi-mediated control of A. tumida.
RESULTS: Injection of V-ATPase subunit A (5 ng) and Laccase 2 (12.5 ng) dsRNAs 
resulted in 100% larval mortality, and qPCR confirmed significant decreases and 
enhanced suppression of transcript levels over time. Oral delivery of V-ATPase 
subunit A dsRNA in solutions resulted in 50% mortality; however, gene 
suppression could not be verified. We suggest that the inconsistent RNAi effect 
was a consequence of dsRNA degradation within the gut owing to the presence of 
extracellular nucleases. Target specificity was confirmed by a lack of effect on 
survival or gene expression in honey bees injected with A. tumida dsRNAs.
CONCLUSION: This is the first study to show evidence for systemic RNAi in A. 
tumida in response to injected dsRNA, but further research is required to 
develop methods to induce RNAi effects via ingestion. © 2016 Crown copyright. 
Pest Management Science © 2016 Society of Chemical Industry.