SFU researchers developing new methods for controlling deadly honeybee parasites

August 16, 2022

Anew chemical compound under development at Simon Fraser University could give beekeepers an edge in the fight against varroa mites, a deadly parasite that affects honeybees.

At her apiary in South Surrey, SFU Chemistry professor Erika Plettner is in the third year of field trials of a new treatment for managing these pests, which have become a serious problem for beekeepers around the world. When left untreated, varroa infestations can cause bee colonies to collapse.

Plettner originally developed the compound, 3c36, to deter moths from feeding on food crops. However, through lab trials she discovered that it can also paralyze mites, causing them to fall off of bees.

Varroa mites jumped from the Asian honeybee to the European honeybee within the last hundred years. From an evolutionary perspective, that timespan is far too short for the bees to develop natural defenses, leaving them very vulnerable to this pest. Since then, infestation has spread worldwide, causing massive damage for commercial beekeepers, and the crops they pollinate.

Plettner points out a mite on one of the sticky sheets her team places at the bottom of hives to assess mite-fall. It’s surprisingly large and easily visible to the eye. She makes a kidney-sized oval with her hands and holds it to her side, the approximate size of the mite relative to the bee. “When it latches on it leaves a very big wound,” she says.

The mites reproduce by feeding on honeybee brood, and once grown, they latch onto adult bees and weaken them. They can also spread viruses, and while the mites only infest honeybee hives, the viruses they introduce can spread to native bees through contact with flowers the insects share, if those flowers are contaminated. “Having very sick honeybees, lots of them, is not a good thing for other insects,” Plettner says. “This is why we as beekeepers have a responsibility to make sure our bees are healthy.”

For the time being, there are only a handful of varroa mite treatments approved for use in Canada. “Any new discovery is met with excitement because you need to rotate different treatments that work in different ways,” Plettner says, “otherwise the mites get resistant, and that can happen fairly quickly, after maybe a decade of use.”

Developing new treatments can be challenging because researchers need to ensure they have a good “therapeutic ratio.” In other words, they will cause harm to the pests, without causing harm to the bees. Not many substances meet this requirement.

“We have a very good therapeutic ratio, which really excites us,” Plettner says, “and we've determined that in several places, with several collaborators so that is what keeps our hopes up.”

The next step is to understand exactly how this compound works on mites before seeking federal approval that it is safe to use, research supported by Genome British Columbia’s Pilot Innovation Fund.

For now, Plettner’s team is continuing to assess the efficacy of this treatment against control groups of hives that are either treated with another commercially available mite treatment, or left untreated. The sticky sheets they place at the bottom of the hives collect the dead mites that they will assess in the lab this winter.

“It’s great to be out here,” Plettner says. “Sometimes we get a bit hot in our bee suits. But the compensation is the birds are signing, we have a lot of flowers flowering. It’s really lovely out here.”

Update, December 4, 2023: SFU and French veterinary pharmaceutical laboratory Véto-pharma have reached an exclusive collaboration agreement to evaluate the effectiveness of compound 3c36.