A study has revealed that heatwaves severely diminish bees' fertility, with significant implications for the pollination of food crops in subsequent years. Researchers simulated a three-day UK heatwave in the laboratory and measured its effect on solitary red mason bees, comparing them with bees kept under control conditions of an ordinary summer.
Study methodology and findings
Prof James Gilbert of the University of Hull and his colleagues subjected one group of red mason bees to heatwave conditions while a control group experienced normal summer temperatures. After nine months, both sets of bees had spun their cocoons and hibernated as usual. However, dissection revealed that the sperm activity of males from the heatwave group had dropped by half compared to the control group. Females in the heatwave group showed a 15% reduction in the size and number of developing eggs.
Impact on solitary bees and food crops
More than 90% of the UK's approximately 270 bee species are solitary and do not have nest-mates to assist them. The findings, published in the Journal of Thermal Biology, suggest 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. Prof Gilbert noted, "The knock-on effect for agriculture could be substantial if heatwaves become more frequent."
Broader ecological consequences
While heatwaves are known to have serious health consequences for humans, this study highlights the vulnerability of other species. The decline in bee fertility not only threatens biodiversity but also the pollination services that underpin many agricultural systems. The researchers emphasize the need for further studies to understand how rising global temperatures may affect insect populations and ecosystem stability.
