Alcohol washes and sugar shakes have been the go-to methods to detect Varroa mite, but a third management system aims to contribute significantly to Australia's management efforts - genetics. Researchers from the CSIRO have been using environmental DNA (eDNA) from hives and honey for early detection of the parasite. Unlike traditional DNA sampling, eDNA is not collected from organisms but from the environment in which they live. As organisms interact with their surroundings, they shed DNA, which accumulates in the environment from various sources like faeces, pollen or mucus. During the COVID-19 pandemic, it was primarily used to detect the presence of the virus in wastewater. CSIRO senior research scientist John Roberts said genetic work with honeybee pests and pathogens had begun many years before the recent incursion on Australian shores. "We were researching in terms of molecular diagnostics, but it wasn't until more recently that we were sort of looking at it through that eDNA lens and understanding how what we're doing is applicable to Varroa mite," Dr Roberts said. "We started some projects around the same time that we had our Varroa incursion, so it was serendipitous that we had already started moving into this space around the same time. "It certainly made it both interesting for us as researchers and a good opportunity, but added a little bit of complexity, where you're really trying to move your science along so it can be as helpful as possible for the incursion." Dr Roberts said he and many other CSIRO had played an advisory role through the early days of the incursion by supporting diagnostics and providing updates on his research. He said eDNA techniques showed much potential, but a lot was still being discovered about the detection sensitivity. But he believed it was "a tool that we should be using" in managing Varroa mite. "There are cases where we know that eDNA doesn't detect something when it's there, so we're trying to understand how it is found in the environment and how we can best detect it for our for our different targets." Genomic technology provider Illumina have installed 380 eDNA sequencers in many Australian research centres. Illumina senior market development manager Evgeny Glazov said a genetics-based approach could free up beekeepers' time. Dr Glazov said Australian researchers have been able to use eDNA to detect varroa mite using a simple cotton swab or a honey sample. "There's certainly work starting on this and I'm sure that not only new basic new research, but transitional research would accelerate in terms of helping to implement practices into a day to day beekeeping, whether it's in relation to developing bee genetics or whether it comes to Varroa mite management," he said. He said eDNA had a significant advantage when identifying early incursions in hives. "There is a more sensitive approach when it comes to detection of an early incursion, which often goes undetected when there are a few bee colonies infected on any given property and relatively few mites in the colony itself," he said. "It can be a tool for more of a sort of passive monitoring, so to speak, where it can be used as part of the routine honey testing... which doesn't mainly disrupt bees during a normal beekeeping operation."
