Beyond chemical miticides: new frontiers against emerging genetic resistance in Varroa destructor mites in Australia

Varroa destructor mites parasitize Western and Eastern honey bees ( Apis mellifera and Apis cerana ) and drive significant colony losses worldwide. In Australia, the recent widespread establishment of Varroa threatens a A$14 billion (~US$10 billion) per annum honey bee industry and agricultural pollination services. Current synthetic miticides used to combat Varroa often target neurotransmitter receptors and ion channels, including pyrethroids (flumethrin, τ-fluvalinate) and amitraz. Alarmingly, Varroa with genetic resistance to both pyrethroids and amitraz have recently emerged in Australia. Beekeepers are now increasingly reliant on non-synthetic ‘soft’ miticides, which are often less effective and negatively impact colony health when used in the high temperatures common across much of Australia. New approaches are clearly needed to combat Varroa . One such next-generation technology is RNA interference (RNAi), in which double-stranded RNA (dsRNA) silences essential genes. RNAi can achieve high species specificity, has a more favorable human and environmental safety profile when appropriately designed, and is less susceptible to genetic resistance caused by target site alteration compared with chemical miticides. RNAi may also trigger immune responses in honey bees which help protect them from viral pathogens. In 2025, the first dsRNA treatment for Varroa (Norroa™) was commercialized in the United States. In silico and in vivo testing to date supports that Norroa™ is species-specific and effective in disrupting Varroa reproduction via targeting the calmodulin gene. However, the active component vadescana does not cause mite mortality and is therefore less effective in cases of high infestation, highlighting the need for other more effective dsRNAs. This review discusses the current state of Varroa control in Australia and exploration of potential dsRNA gene targets. We will discuss the necessary next steps for dsRNA miticide testing and propose new gene targets for further development.