Bees Ejaculating Themselves to Death in Heat Waves: Viral Story Explained

Bees across Europe may die from the severe heat plaguing the continent this week, ejaculating explosively as they do so.

In the U.K. and parts of mainland Europe, temperatures have recently soared up to 104 degrees Fahrenheit in one of the hottest heat waves since records began. This heat, while dangerous for humans and animals alike, may have particularly bad effects on the honey bee populations we rely so heavily upon.

As reported in several stories that have gone viral, in severe heat, male honey bees could face a terrible fate: they begin to convulse, ejaculate explosively, then die. At temperatures over 107 degrees Fahrenheit, it is estimated that half of male honey bees will die in this manner within six hours, with more sensitive individuals dying after only two or three hours.

"We don't know exactly why, but drones ejaculate when they get too stressed," Dr. Alison McAfee, a postdoctoral fellow at the University of British Columbia's Michael Smith Laboratories, told Newsweek. "Ejaculation kills them because it basically eviscerates their abdomen. This happens during natural mating too—drone honey bees always die after mating."

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A dead male honeybee, having ejaculated from heat shock. Emily Huxter.

The bees cool down their hives naturally, keeping it at around 95 degrees Fahrenheit. During heat waves, however, the balance is lost, and the males begin to die.

These unfortunate male bees tend to be more sensitive to environmental stressors like temperature, according to research published in the journal Communications Biology in February. The study suggests that this may be because male honey bees are haploid drones, meaning that they have half as many chromosomes DNA as female worker bees. This has previously been thought to make the males more vulnerable to biotic threats including pesticides, and now, it seems that temperature may also affect males more.

Males may not make honey like the female worker bees, but they are essential to the hierarchy of the hive.

"High quality male honey bees are essential for supporting adequate mating of queens, whose longevity depends on the number and quality of sperm acquired during nuptial flights," said the authors in the Communications Biology paper.

"The fact that drones die in the heat means that as heatwaves continue to become more intense, longer and more frequent, there may be fewer drones around to mate with new honey bee queens," McAfee told Newsweek. "This could be a problem for queen production, which is a big chunk of the industry."

If honey bee hives begin to fail, there could be severe consequences on both biodiversity and the economy. Honey bees are hugely important to the agricultural industry, as they are one of the major pollinators of over 100 food crop varieties in the U.S. The global honey market was also worth around $8.58 billion in 2021.

McAfee and a beekeeper colleague Emily Huxter have been working on methods to help the hive stay cool to prevent these mass male deaths. They found that coating hives in two-inch polystyrene covers decreased the internal temperature by almost 4 degrees Celsius compared to control hives, and those who were fed with syrup were about 1 degree cooler.

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A bee having ejaculated to death. Dr. Alison McAfee

"I am more worried about how fertility of other insects, like bumblebees or solitary species, may be impacted by the heat," McAfee told Newsweek. They are not as good as honey bees at thermoregulating, and don't have beekeepers around to help insulate their homes."

Bumblebees may also be severely affected by increasing heat wave frequencies due to climate change.

"Their large size and furry coat are adaptations to thriving in cool conditions—bumblebees are most common in temperate, montane and polar regions, and few can survive in the [Mediterranean ]," Dave Goulson, bee ecologist and professor of biology at the University of Sussex, in the U.K., told Newsweek.

"They overheat in very warm weather, and simply cannot fly—imagine trying to flap your arms 200 times per second while wearing a fur coat. Modeling suggests that many common U.K. species will not be able to survive in the U.K. under likely future climate scenarios."

Heat waves and droughts have become increasingly more common due to the climate change effects caused by carbon dioxide emissions.

Update 7/20/22 3:13 a.m. EDT: This article had been updated with comment from Dr. Alison McAfee, postdoctoral fellow at the University of British Columbia.