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Climate Change Is Ratcheting Up the Pressure on Bees

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honey bee closeup on berry
A honey bee forages on a lemonade berry sumac shrub. (Getty Images)

The extreme weather that has in 2022 doesn鈥檛 just affect humans. Heat waves, wildfires, droughts and storms also 鈥 including some that already face other stresses.

I鈥檝e been for over 10 years, with a focus on honeybees. In 2021, I began hearing for the first time from beekeepers about how extreme drought and rainfall were affecting bee colony health.

in 2021 dried up bee forage 鈥 the floral nectar and pollen that bees need to produce honey and stay healthy. And limited the hours that bees could fly for forage.

In both cases, managed colonies 鈥 hives that humans keep for honey production or commercial pollination 鈥 were starving. Beekeepers had to feed their bees more supplements of sugar water and pollen than they usually would to keep their colonies alive. Some beekeepers who had been in business for decades shared that they lost 50% to 70% of their colonies over the winter of 2021-22.

woman takes photo of salvia and pollinators in garden
Student intern for the 嘿嘿视频 Arboretum Elizabeth Hursch collects iNaturalist images of pollinators with her cell phone in 2021. (Gregory Urquiaga, 嘿嘿视频)

These weather conditions . And unlike managed colonies, these important species did not receive supplements to buffer them through harsh conditions.

Each year, the and the host federal pollinator experts to share the latest scientific findings on bee and pollinator health, and assess the status of these important insects, birds, bats and other species. One clear takeaway from this year鈥檚 meeting was that climate change has become a new and formidable stressor for bees, potentially amplifying previously known issues in ways that scientists can鈥檛 yet predict but need to prepare for.

Climate change threatens bees around the world. In Australia, large-scale bush fires and drought have killed millions of bees in recent years.

The scourge of Varroa mites

Pollinators contribute yearly to global agriculture, based on the value of the crops they pollinate. Understanding and mitigating the impacts of climate change on pollinators is key for supporting healthy ecosystems and sustainable agriculture.

Planting  with regional plants that bloom throughout the year can provide much-needed forage.

Bee health first attracted widespread attention in 2006 with the emergence of , a phenomenon where the majority of adult worker bees in a colony disappeared, leaving their honey and pollen stores and some nurse bees behind to care for the queen and remaining immature bees. In the past five years, reported cases have declined substantially. Now, researchers are focusing on what beekeepers call the 鈥渇our Ps鈥 鈥 parasites, pathogens, pesticides and poor nutrition 鈥 as well as habitat loss for wild and native bees.

One of the most severe threats to honeybees over the past several decades has been Varroa destructor, a crablike parasitic mite that . The fat body is that functions much like the liver in mammals. It helps bees maintain a strong immune system, metabolize pesticides and survive through the winter.

These are vital functions, so controlling mite infestations is essential for bee health. Varroa can also transmit deadly pathogens to honeybees, such as .

A honeybee carrying two Varroa mites, one above its leg and one on its back. )

Controlling mite populations is challenging. It requires using an insecticide in an insect colony, or as beekeepers say, 鈥渢rying to kill a bug on a bug.鈥 It鈥檚 hard to find a formula strong enough to kill mites without harming the bees.

Monitoring Varroa takes significant skill and labor, and mites can build up resistance to treatments over time. Researchers and beekeepers are working hard to , but mites continue to plague the industry.

Pesticide microdoses

Pesticides also harm bees, particularly products that cause sublethal or chronic bee health issues. can make bees less able to , and and mites.

However, it can be hard to document and understand sublethal toxicity. Many factors affect how bees react to agrochemicals, including whether they are exposed as larvae or as adult bees, the mixture of chemicals bees are exposed to, the weather at the time of application and how healthy a bee colony is pre-exposure.

Researchers are also working to understand , which represent population.

A ground-nesting bee (Colletes inaqualis) emerging from its burrow. (, )

Junk food diets

Like many other species, bees are losing the habitat and food sources that they depend on. This is happening .

For example, uncultivated lands are being . Large-scale agriculture focuses on mass production of a few commodity crops, which reduces the amount of nesting habitat and forage available for bees.

And many farmers often remove pollinator-friendly plants and shrubs that grow around farm lands to reduce the risk of attracting animals such as deer and rodents, which could . Research suggests that these efforts .

As diverse and healthy bee forage disappears, beekeepers , such as sugar water and pollen substitutes, which are as the nectar and pollen bees get from flowers.

Climate change is a force multiplier

Researchers don鈥檛 know exactly how climate change will affect bee health. But they suspect it will add to existing stresses.

For example, if pest pressures mount for farmers, bees will be exposed to more pesticides. Extreme rainfall can . Wildfires and floods may destroy bee habitat and food sources. Drought may also and from planting new areas for bees as water becomes less readily available.

Most importantly, educating people and communities about bees and their importance to our food system can help create a more pollinator-friendly world.

Climate change could also increase the spread of Varroa and other pathogens. Warmer fall and winter temperatures . Varroa travel on foraging bees, so longer foraging provides a larger time window for mites and the viruses they carry to spread among colonies. Higher mite populations on bee colonies heading into winter will likely cripple colony health and .

Studies have already shown that climate change is between bees and flowers. As spring arrives earlier in the year, or in different regions, but bees may not be present to feed on them. Even if flowers bloom at their usual times and locations, they may under extreme weather conditions.

Research that analyzes the nutritional profiles of bee forage plants and how they change under different climate scenarios will help land managers plant climate-resilient plants for different regions.

Creating safe bee spaces

There are many ways to support bees and pollinators. Planting with regional plants that bloom throughout the year can provide much-needed forage.

Ground-nesting native bees need patches of exposed and undisturbed soil, free of mulch or other ground covers. Gardeners can clear some ground in a sunny, well-drained area to create dedicated spaces for bees to dig nests.

Another important step is using , a land management approach that minimizes the use of chemical pesticides. And anyone who wants to help monitor native bees can join and use phone apps to submit data.

Most importantly, educating people and communities about bees and their importance to our food system can help create a more pollinator-friendly world.The Conversation

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