Pollinators, essential players in our global food systems, are continuing to face significant threats. This year, beekeepers in the United States reported the loss of nearly half of their managed honey bee colonies. Loss of habitat, pesticide use, climate change, and pests and pathogens have all been identified among the causes of this decline.

Now a growing body of literature is showing that air pollution, generally thought of as mainly a threat to humans, also significantly impacts the health of honey bee colonies. New research underscores the alarming effects of air pollution on bees’ foraging efficiency, memory, and overall health.

Ground-level Air Pollution

Ground-level atmospheric ozone is a main air pollutant and the primary component in urban “smog”. In high concentrations, ozone is already known to cause respiratory problems in humans and reduce yields and growth in plants.

Nitrogen oxide (NOx), produced by burning fossil fuels, is another common pollutant that has the potential to significantly reshape ecosystems and affect pollinators. NOx, along with atmospheric nitrogen, adds excess nutrients to the environment, changing ecosystems and reducing the diversity of pollinator host plants. Studies have also shown an increase in dead and injured bumblebees in colonies that visited plants enriched with excess nitrogen.

Ozone’s Effect on Honey Bees

Several pollinators, including honeybees, locate and identify flowers by using their antennae to recognize Volatile Organic Compounds (VOCs) in the air. What we think of as the scents of flowers, are really molecules that are carried by the wind and air over long distances, creating trails for pollinators to follow.

In a recent study, scientists found that increased ozone concentrations affected the emission of VOCs by plants, changing how long they remained present in the air. Their findings also showed that exposure to ozone leads to decreased antenna activity, and a reduction in the honey bees’ ability to recall scent. This means that not only do the scents of flowers become harder to detect, but the bee's ability to pick up on scents is also reduced, making it harder for them to find and remember food sources. Colonies depend on scout bees to find flowers in bloom, remember their location, and return to the hive to share the information with forager bees who then return en masse. The researchers also identified for the first time that ozone decreased the amount of superoxide dismutase enzyme, an antioxidant that protects bees from oxidative stress.

This study supports the findings of earlier research, which has shown that exhaust fumes from cars, which cause the creation of ozone and NOx in the air, led to an 83-90% decrease in flower visits by pollinators. Further studies have also shown that pollinators can be harmed by particulate pollution. Fine, electrically charged hairs on bees’ bodies, designed to attract pollen, can also draw in other small particles such as dust and heavy metals.

Why do Pollinators Matter?

Pollinators are not just important in natural ecosystems, they are also indispensable workers in the global food system. According to the UN Food and Agriculture Organization, a third of the world's food production depends on bees.

Honeybees also provide us with honey (roughly 1.8 million tons annually), royal jelly, beeswax, bee bread, pollen, propolis, and honey bee venom. The 2019 Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) report emphasizes, “Sacred passages about bees in all the worlds’ major religions highlight their significance to human societies over millennia.”

Warning Signs for Ecosystems

By understanding the effects of air pollution on honey bees, we may be able to use some of the more than 100 million bee colonies across the world as bio-detectives, providing a window into the health of other pollinators and ecosystems at large. Honey bees appear to be acutely sensitive to air pollution, displaying changes in behavior even at average environmental ozone concentrations, and more extreme responses when levels peak.

As the only pollinators that live in such large colonies, honey bees can be used to monitor how environmental changes may be impacting the vast majority of pollinating insects that live seasonally in solitary burrows.

Using Data to Understand Pollinator Health

BeeSage’s technology enables beekeepers to efficiently collect data on key parameters like beehive weight, temperature, humidity, sound, and location. These indicators are used to gauge the health of the colony, combining that information with the anonymized data from other hives to produce a nuanced picture of regional pollinator health.

Weight fluctuations indicate changes in honey production and brood rearing, while temperature, sound, and humidity provide insights into how the colony is responding to external stress factors. By using open-source air pollution geodata, we also hope to be able to better inform beekeepers and researchers on the presence and effects of potentially harmful air pollution in the environment.

Understanding the threats faced by honey bees and other pollinators is essential for researchers, beekeepers, and farmers to be able to continually plan and adapt to changing conditions. Their work is key to achieving UN Sustainable Development Goal 2, ensuring secure global food systems in a changing world.

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