Some of Australia’s native bees may be far more vulnerable to climate change than others, and the key difference comes down to where they sleep.
Bees that nest inside exposed plant stems have almost no way to escape extreme heat. Those that burrow underground can simply hide from it. A new study of 95 native bee species across eastern mainland Australia, from the tropical north to cooler southern zones, reveals that nesting location may determine which bees survive a warming world.
Stem nesters have nowhere to go
Researchers from Macquarie University, The University of Sydney, La Trobe University, Flinders University, University of Wollongong, Adelaide University, and The University of Queensland examined heat tolerance in bees collected from locations spanning much of eastern Australia. They found that bees fall into three nesting groups: ground burrowers, wood cavity users, and stem nesters.
Stem nesters build their homes inside thin plant stems or small holes in twigs. These materials offer very little insulation. When outside temperatures rise, the bees inside heat up quickly and cannot escape. Underground nesters, by contrast, can retreat deeper into the soil where temperatures stay cooler. The study, published in Nature Communications, suggests that stem nesting species have the lowest capacity to avoid unfavorable temperatures and are likely to be the first affected by human caused climate change.
Tropical bees are especially at risk
The research also uncovered a geographic pattern. Bee species living closer to the equator, in tropical parts of Australia, showed higher vulnerability even though they are already adapted to hot environments. This means that simply being used to heat does not protect them from extreme temperature spikes. The combination of tropical location and stem nesting behavior creates a double threat.
Australia is home to about 1,700 native bee species. Many of them are vital pollinators for both natural ecosystems and agriculture. Tropical native bees help pollinate crops such as macadamia nuts, avocados, mangos, and lychees. If stem nesting bees decline, those crops could lose a key source of pollination.
The study’s lead author, Dr. Carmen da Silva from Macquarie University, noted that bees are critical worldwide because of their role as pollinators, and they are under threat from warming and drying climates. The findings indicate that behavior, not just biology, matters when predicting which species will survive.
What this means for the future
Not all bees face the same future. The study makes clear that stem nesting species are likely to be the most impacted in the near term. Their inability to escape heat, combined with rising global temperatures, puts them in a precarious position. Underground nesters, by contrast, have a built in refuge. As the climate continues to warm, the bees that cannot hide may be the first to disappear.
