Gene Silencing Varroa Control Proposed in the US, with Support from NZ

A New Zealand university has played a critical role in a cutting-edge new varroa treatment which recently took one giant step closer to being fully approved for beekeeper use in the USA.

‘Vadescana dsRNA’ has been moving through the steps of approval for use in America over the last two years. As of May 29 the Environmental Protection Agency (EPA) has proposed the gene silencing product fit for registration, while calling for more public comment before implementing the approval.

A pouch of sugar syrup, complete with Vadescana dsRNA, is applied to beehives in America, where the EPA has moved it close to being fully registered for beekeeper use.

In that time, more than 40 individuals and groups – including several State beekeeping associations in support – have lodged submissions. One of those is Prof. Phil Lester of Victoria University of Wellington, who is in support of making the double stranded RNA (ribonucleic acid) interference (dsRNAi) product available for the use of US beekeepers.

“Our studies here in New Zealand have shown Vadescana to have significant potential as a targeted biopesticide. It appears to have substantial value as a tool in the beekeeper’s toolbox for varroa control,” Lester’s submission states.

The Wellington university has been working with Vadescana’s developer – GreenLight Biosciences, an American company which specialises in development of RNA products for use in primary industries – by conducting both lab tests and field trials in New Zealand since 2021.

The product is administered to honey bee hives through sugar syrup, contained in a pouch placed in the hive. The active ingredient is then transferred from bees to varroa mites, resulting in disruption of the mite’s breeding cycle. No fewer than four of Lester’s team of researchers presented various findings to the New Zealand apiculture industry at the 2024 Honey Bee Research Symposium, including findings Vadescana dsRNAi treated honey bees lived longer and foraged more actively.

Lester’s submission to the US EPA states they have conducted in-laboratory research with Vadescana which can induce “a near complete knock-down of varroa reproduction” while field trials “have shown Vadescana to have a good ability to maintain low mite numbers”.

Gene silencing technology does not fall into the category of genetic modification or engineering and thus research can be conducted in New Zealand without approval.

Prof. Phil Lester of Victoria University of Wellington has led New Zealand research into gene silencing varroa control agent ‘Vadescana’ since 2021, backed by GreenLight Bioscience, and says the company has began working towards registration in New Zealand.

There appears to be widespread support for registration of Vadescana, with several state or regional beekeeping associations affirming the product’s registration in the US, as well as heavier hitting national groups, led by the US Department of Agriculture. However, concerns of harm to honey bees have been raised by beekeeping groups such as the Pollinator Stewardship Council, as well as the American Beekeeping Federation. Lester’s submission addressed those concerns head on.

“I believe their comments appear to come from a misunderstanding of the RNAi technology and their concerns regarding the use of dsRNA are not relevant in pest management. They seem to believe that dsRNA would be the equivalent of a virus, with the ability to replicate, evolve and mutate. Such a belief is totally incorrect,” The Victoria University of Wellington professor states.

Speaking to Apiarist’s Advocate on the topic, Lester provides further context.

“There is understandable concern about this pest management method, largely because it is new and, for some, because it contains the word ‘gene’, as in gene silencing. This is indeed a novel approach, and unlike conventional methods, we don’t yet have decades of field use to draw on. And perceptions are often influenced by how something is named. For example, if we began referring to Bayvarol and Apivar as ‘neurotoxins that damage or disrupt nervous system functioning’ — which is what they are and what they do — public perception of those treatments might shift as well.

“Some submissions appear to confuse gene silencing approaches with viruses, raising concerns that the Vadescana treatment could somehow mutate. But these are not viruses — and there is no mechanism for mutation. It simply cannot happen,” he says.

While the US – home to GreenLight Bioscience, approximately 2.7million beehives, and widespread colony die-off in large part due to varroa – is an ideal place to launch Vadescana, New Zealand is also on the radar.

“GreenLight have begun the process of working with the EPA in New Zealand for registration here. That process may take some years, and it will involve opportunity for public submission and consultation here as well,” Lester says, adding “If it is successfully registered in the US and used there, we will then have more experience and user-information to add to the evaluation process here”.