6 May 2024

A step forward in the fight of bees against mites


Canadian study provides new details on the interaction between bees in their post larval stage and the Varroa destructor, a mite capable of destroying up to 40 percent of pollinator colonies each year

by Matteo Cavallito


Bees are known to play a vital role in the ecosystem as a whole and are an indispensable factor in global agriculture. It is not surprising, then, that combating pests that attack pollinators is a priority for operators. To this end, a deep understanding of the mechanisms that characterize the interaction between bees themselves and their natural enemies appears crucial.

Now, in a study published in the journal Nature Communications, researchers at the University of Alberta, Canada, who have provided new information on the actions of the Varroa destructor, a particularly dangerous mite that is responsible for an estimated 30 to 40 percent of the country’s pollinator colonies that are lost annually.

Feeding varies over the life cycle of bees

To effectively control the action of the mite, the researchers remarked in a statement from the university, it is necessary to know when and what the mite feeds on during the bee’s life cycle. In the past, Varroa was thought to take up the bee’s hemolymph or blood throughout its development. In 2019, however, a University of Maryland study had revealed that the mite feeds on a layer of fat present in the bee just below the exoskeleton. The research, however, had focused on adult bees.

Nothing, until now, was known, however, about the mite’s behavior with pupae, that is, bees in the post larval stage prelude to their emergence from the cell.

Studying the interaction between the parasites and the insects, a team of scholars led by Olav Rueppell, a researcher in the Department of Biological Sciences at the University of Alberta, has shown that at that particular time in the life cycle it is the hemolymph that feeds the mites. What has been judged in recent years as an outdated hypothesis, in other words, would instead find confirmation, even if only in the case of younger pollinators. “Getting that relationship right is crucial for coming up with control measures to eradicate the pest,” the authors explain.

Not just pesticides

Bees and mites, Rueppell says, “are both basically bugs and so closely related … it’s very hard to kill one without killing or harming the other, and as much information as we can get will help us.” The goal is to improve defense strategies, which, at the moment, come through the use of pesticides – with all the inevitable tradeoffs – and enhancing the responsiveness of the pollinators themselves.

The researchers particularly hope that a better understanding of the dynamics of mite nutrition will give them an advantage in controlling the pest.

This is an essential issue, recalls Rueppell, who stresses the importance of pollinators to the agricultural sector. “Bees pollinate a lot of our food supply and commercial crops, such as canola”, he explains. “Their impact in Canada is worth more than $3 billion each year.”

A Day for Pollinators

The centrality of bees in the global food system has long been known as well as the urgency of finding solutions to protect them. The United Nations, not surprisingly, has chosen to dedicate a Day to these precious insects that is celebrated worldwide on May 20 every year. An occasion, in short, to celebrate the magnitude of their contribution while raising awareness of the dangers of downsizing their presence.

Bees, both domestic and wild, play a crucial role in pollinating 70 percent of the Planet’s plant species and contribute 35 percent of global food production. The loss of these pollinators, fostered by critical factors such as climate change, disease, pesticide use and loss of natural habitats, would inevitably lead to a drastic reduction in plant biodiversity. And it would significantly increase agricultural production costs because of the need to resort to artificial pollination methods.