Varroa mite parasites cause major problems for honey bees - and beekeepers. Now, New Zealand researchers are investigating a new type of RNA-based treatment that could make treating varroa mite infestations easier, as well as better for the bees and the environment.

Varroa destructor mites are bad news for honey bees.

Not only do they attack the bees by chewing on a vital organ called the fat body, but they also introduce problematic viruses to the hive - such as deformed wing virus, which does exactly what it says on the tin.

Beekeepers worldwide must treat for varroa mites several times a year just to keep their numbers in check. They mostly use pesticides, which can have damaging effects on the bees and environment. The mites are also beginning to develop resistance to pesticides, but a new treatment method may be just on the horizon.

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RNA interference

This is what PhD candidates Zoe Smeele and Rose McGruddy have been researching. Under the supervision of Professor Phil Lester, they've been working with US biotechnology company Greenlight Biosciences to investigate how their new treatment for varroa mites works.

The treatment is based on a technique called RNA interference. An interesting bio-hack that researchers have figured out is how they turn a natural virus defence mechanism in the cell against one of the mite's vital proteins.

Greenlight Biosciences were able to identify a working treatment that reduced mite numbers in field trials in the states but turned to the New Zealand researchers for help in uncovering exactly how it works.

Mini-hive experiments

In one of the research labs in the School of Biological Sciences at Te Herenga Waka Victoria University of Wellington, Zoe and Rose have been conducting mini-hive experiments. Their participants are larval stage bees taken from the hives on the roof of the building, infected with varroa mites.

The nurse bees that feed the larvae are given plastic pouches full of sugar water with the RNA interference treatment inside. What the team has discovered is that instead of killing the mites, what the treatment does is severely impact the mites' reproduction.

But what about real beehives?

Initial field trials with New Zealand beekeepers have showed some promise, but also highlighted that there's much to learn in terms of the dosage per bee. A next round of trials is just getting underway, and this will also include RFID tagging of bees to monitor any impacts at the individual bee level. …

Go to this episode on rnz.co.nz for more details