A study has revealed that extreme heatwaves severely reduce bee fertility, with significant implications for the pollination of food crops in subsequent years. Researchers at the University of Hull simulated a three-day UK heatwave in the laboratory and measured its effect on solitary red mason bees compared with those kept under normal summer conditions.
Sharp decline in sperm activity
After nine months, both groups of bees had spun their cocoons and hibernated normally. However, dissection revealed that the sperm activity of males from the heatwave group had dropped by 50% compared to the control group. Females exposed to the heatwave showed a 15% reduction in the size and number of developing eggs. The findings were published in the Journal of Thermal Biology.
Impact on solitary bees and crop pollination
More than 90% of the UK's 270 or so bee species are solitary and lack nest-mates for support. This makes them particularly vulnerable to environmental stressors. Prof James Gilbert of the University of Hull and his colleagues noted that a heatwave could lead to a significant drop in bee populations the following year, resulting in less efficient pollination for key food crops such as apples and oilseed rape.
The study underscores the broader ecological consequences of extreme heat events, which are becoming more frequent due to climate change. While the health impacts of heatwaves on humans are well-documented, this research highlights similar threats to vital insect pollinators.
