Bumble bees lose their sense of smell after heat waves

Heat waves, intensified by climate change, not only warm bumblebees but also significantly impair their sense of smell, which is crucial for their survival. Sabine Nooten and her team at the University of Würzburg found that simulated heat waves decreased bumblebee antennae’s ability to detect floral scents by up to 80%. This reduction in olfactory sensitivity could hinder bumblebees’ foraging efficiency, jeopardizing their colonies’ survival.

Exposure Experiments and Findings

In their August research publication in the Proceedings of the Royal Society B, Nooten’s team examined around 190 bumblebees from two species—Bombus terrestris and B. pascuorum. They were placed in tubes at temperatures of 40° Celsius for nearly three hours, mimicking heat wave conditions. The results showed a substantial drop in their antennae's sensitivity to three key floral compounds—ocimene, geraniol, and nonanal—by up to 80%. Importantly, the bees did not regain their olfactory abilities even after a 24-hour recovery period in cooler environments, a finding deemed alarming by the researchers.

Implications for Ecosystems and Agriculture

The consequences extend beyond bee colonies to human agriculture. Bumblebees are vital pollinators for about one-third of our food crops, including vegetables, fruits, nuts, and legumes. Reduced pollination efficiency, caused by such sensory loss, could lead to a decline in crop yields. Habitats and climates that bees thrive in are worsening due to more frequent and severe heat waves, posing a dual threat to bee populations already struggling from habitat loss.

Future Directions and Broader Impact

Researchers point out that the antennae functionality across different bee species appears similar, suggesting that if bumblebees suffer olfactory losses due to heat, other bee species might as well. Further research is anticipated to explore this effect on diverse pollinators like hoverflies. According to field ecologist Coline Jaworski and molecular ecologist Sandra Rehan, understanding these physiological impacts can guide strategies to mitigate climate change's adverse effects on pollinators.

In summary, climate-induced heat waves significantly impair bumblebees' sense of smell, potentially disrupting their foraging patterns and affecting broader ecosystems, including human food crops. Combating this issue requires adaptive strategies and continued research into the specific vulnerabilities of various pollinators.

Earlier, SSP wrote about a new perspective on horse domestication.