There is not yet much research on the effects of heatwaves on bees. What little there is focuses on super extremes of weather that would kill an adult bee.

However, my new research with colleagues shows that UK populations of solitary bees may be much more sensitive than previously thought to the kinds of extreme weather we are now seeing regularly.

To find out what happens to bees during hot weather, my team recreated the three-day UK heatwave of July 2022. We subjected a group of developing larvae of red mason bees to three days where temperatures peaked daily at 40°C.

Red mason bees are common solitary bees found in UK gardens, and are important pollinators of apples and other fruits. At the same time, a control group experienced normal July temperatures for Hull, where the study was conducted, peaking daily at about 25°C.

After that, we treated both groups identically and allowed them to spin their cocoons and hibernate as normal. Nine months later, all the bees emerged fine, so it appeared initially that the heatwave had had no effect.

But this was before we dissected the bees to look at their reproductive health.

Staggeringly, in males from the heatwave........

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