Bourdon mort

Bees ‘ejaculate’ their abdomens to death in hot weather

Each species has its own way of reacting to the extreme conditions encountered in nature. For bees, more specifically bumblebees, their reaction to high temperatures can be quite gory.

Generally, when observing a dead bee, it may appear partially exploded. It turns out that when bumblebees die from extreme heat, their last act is to “ejaculate” part of their own abdomen.

Dr. Alison McAfee, a postdoctoral fellow at UBC’s Michael Smith Laboratories and an expert in bee health, claimed that when bumblebees die from shock, they ejaculate spontaneously, externalizing an endophallus having about the size of their own abdomen.

The effects of heat

In a study evaluating bee mortality during intense heat waves in British Columbia, McAfee and his team tried to find ways to cool hives to prevent this macabre phenomenon. Indeed, in 2021, following a significant rise in temperature, a beekeeper contacted the team of researchers after noting the death of some of his bees. It would seem that several similar deaths have been observed in the region, especially in the small starter colonies called “nucs”.

If in general, the monitoring of the environment of bees is based on the surveillance of their queens, the researchers realized that the death of bumblebees should not be neglected. According to McAfee, after exposure to a temperature of 42°C for 6 hours, half of the bumblebees will die from heat stress. Moreover, the most sensitive begin to perish after 2 to 3 hours. It’s a temperature condition they wouldn’t normally experience, but scientists have seen bumblebees that were stressed to death.

serious consequences

The situation is serious because in addition to decreasing the resources to create new hives, a limited number of bumblebees is equivalent to a lower genetic diversity. This could lead to lower resistance to diseases, as well as other problems.

Furthermore, during the heat wave studied, only 40% of the queens mated successfully, compared to 75 to 80% under more favorable conditions. To overcome these problems, McAfee and his colleagues tested several methods of cooling the hives while constantly monitoring the colonies.


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