Major cause of honeybee mortality can be easily reduced

Honey bees play a vital role in pollination, supporting food production and maintaining biodiversity. However, their populations have been declining due to multiple threats, including habitat loss, pesticides, and climate change. Among these dangers, one menace stands out – Varroa destructor mites.

These parasites latch onto honey bee larvae, weakening entire colonies and leading to their collapse. Beekeepers have long battled these mites using various treatments, but a new study reveals that improper timing of these treatments could be causing more harm than good.

Researchers at the University of Exeter found that many beekeepers are not following recommended treatment schedules. As a result, their hives suffer higher losses than necessary.

The findings suggest that improving adherence to treatment guidelines could make a significant difference in bee survival rates.

Varroa mites are killing bees

The study analyzed data from 4,339 beekeepers across 37 counties in England and Wales. Using information from the National Bee Unit’s BeeBase, the researchers examined 18,700 colonies between 2016 and 2020.

By tracking Varroa mite treatments, they found that the type of treatment used was important, but its timing played an even greater role in determining colony survival. Delayed or premature applications led to a higher rate of hive losses, regardless of the treatment method.

“The main finding here was that a major cause of honeybee mortality could, in theory, be quite easy to reduce,” said Dr. Thomas O’Shea-Wheller, lead author of the study from the University of Exeter.

The research challenges the assumption that the main threats to honey bees come from new diseases or environmental changes. Instead, it points to an overlooked but controllable factor – adherence to treatment schedules.

Breaking the reproductive cycle

Mite populations increase rapidly throughout the beekeeping season, growing in an exponential pattern. This makes it essential for beekeepers to apply treatments at the correct moments to break the reproductive cycle of the mites.

“Although beekeepers are frequently treating for Varroa, a considerable proportion are missing key time points and thus experiencing higher losses than expected,” said Dr. O’Shea-Wheller.

A common mistake among beekeepers is applying treatment too early or too late in the season. If treatment occurs too soon, it may not fully eliminate the mites, allowing them to rebound before the season ends.

If applied too late, the mites will have already caused significant damage to the colony.

Untimely treatment leads to more bee deaths

Varroa mites weaken honey bees by feeding on their bodily fluids, which reduces their ability to fight infections and diseases. As the mite population grows unchecked, the hive becomes more vulnerable to collapse.

“If you miss these, and apply a treatment too early or too late, then it will fail to properly suppress the mite population and growth will continue unchecked,” said Dr. O’Shea-Wheller.

“Missing the recommended treatment window is, I think, the largest cause of poor prognostic outcomes and associated colony mortality.”

This mistiming does not just impact individual hives. The spread of Varroa mites from poorly treated colonies can affect neighboring hives, creating a wider problem for beekeeping communities.

Growing threat of resistance

Beyond colony losses, inconsistent treatment schedules also contribute to another serious issue – the rise of resistant Varroa mites. Similar to antibiotic-resistant bacteria, mites that survive mistimed or improperly applied treatments become more resistant to future applications.

“Varroa has been the primary cause of honey bee mortality for some years, and it seems that we’re in a sort of arms race as the mites become increasingly resistant to acaricides,” said Dr. O’Shea-Wheller.

“Like with antibiotics, it’s important to use Varroa treatments precisely as directed, because mistiming, overdosing, or underdosing can all increase the chances of the mites developing resistance.”

This resistance forces beekeepers to rely on stronger or alternative treatments, which may not always be effective. If resistance continues to spread, managing Varroa mites will become even more challenging in the future.

A simple yet effective solution

The research suggests that improving adherence to treatment guidelines could significantly reduce colony losses.

Unlike other threats to honey bees, such as climate change or habitat destruction, this is a problem that can be addressed immediately.

By ensuring that treatments are applied at the right time, beekeepers can not only protect their own hives but also help slow the spread of resistant mites. This change requires greater awareness, education, and commitment from beekeepers to follow best practices.

Protecting bees with timely Varroa treatment

Honey bee populations face a range of threats, but the study highlights one key factor that can be controlled right away. Proper timing of Varroa mite treatments is a simple yet powerful step toward reducing colony losses.

With continued research and better adherence to treatment schedules, beekeepers can play a crucial role in safeguarding these vital pollinators. The future of honey bees depends on proactive solutions, and ensuring timely Varroa treatment is a crucial part of that effort.

The study is published in the journal Entomologia Generalis.

Image Credit: Fera Science

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