They cannot burrow underground or hide in a hollow. They are trapped.
Across Australia's vast and varied landscapes, the fate of more than 1,700 native bee species is being written not only by rising temperatures, but by the quiet choices of where each bee makes its home. Research led by evolutionary physiologist Carmen da Silva reveals that a bee's nesting behavior — whether it burrows into cool earth or inhabits an exposed plant stem — may determine its capacity to endure a warming world. The most heat-tolerant bees, paradoxically, are the most endangered by heat, while tropical species, already living at the edge of what their bodies can bear, face the narrowest margin for survival. In this story, biology and geography conspire together, and the stakes extend far beyond the bees themselves — to the crops, ecosystems, and food systems that depend on their quiet, essential labor.
- Australia's native bees are being pushed toward a thermal threshold they did not evolve to cross, with tropical species already living so close to their biological limits that even modest temperature rises could prove fatal.
- The varroa mite has already devastated commercial honeybee hives across Queensland, making native bees the continent's last reliable pollination safety net — one now threatened by the very climate crisis accelerating alongside it.
- A cruel irony sits at the heart of the research: stem-nesting bees, the most physically heat-tolerant, are also the most exposed, with no underground refuge to retreat to when temperatures spike beyond survival.
- Ground-nesting bees — roughly 70 percent of Australia's native species — hold a geographic advantage, able to descend into cooler soil when surface heat becomes lethal, giving them a resilience their bodies alone could not provide.
- Scientists are calling for conservation strategies that engineer cool microclimates for vulnerable species, but warn that without meaningful emissions reductions, such measures may only delay an outcome that evolution cannot outrun.
Carmen da Silva chases native bees across Australia with a butterfly net — from Adelaide's suburbs to Cape York's rainforests — trying to understand which species will survive what's coming. As an evolutionary physiologist at Macquarie University's Pollinator Futures Research Centre, her answer is both precise and unsettling: survival depends almost entirely on where a bee chooses to live.
Her team's research produced a counterintuitive finding. Stem-nesting bees — those that live inside exposed plant stems — are actually the most heat-tolerant of all native species. Their bodies have evolved to withstand extreme temperatures. But in a warming world, that physiological strength becomes a trap. When heat arrives, they have nowhere to go. They cannot burrow. They cannot hide. They are stranded in their own homes.
Ground-nesting bees face a different equation. Though their bodies are generally less heat-tolerant, roughly 70 percent of Australia's native bees nest underground, where cool soil offers refuge when surface temperatures become lethal. Geography, in this case, compensates for biology.
Tropical species face the gravest risk of all. Having evolved to live near the upper boundary of what their bodies can tolerate, they carry no margin for error. Even small temperature increases push them past the threshold of survival — the cruelest irony of climate change, that the animals most shaped by warmth are the least able to absorb more of it.
The consequences reach well beyond the bees. Australia's 1,700-plus native species pollinate crops and wild plants that hold ecosystems together. Stingless bees are critical to tropical fruits and nuts — macadamias, lychees, watermelons. With Queensland's commercial honeybee populations devastated by the varroa mite, native bees have become the continent's agricultural insurance policy.
Da Silva is careful to note that native bees can adapt — but only across generations. Evolution cannot be rushed. Individual bees cannot acclimatize within their own lifetimes, which means the window for meaningful intervention is narrow. Conservation must focus on creating cool microclimates for the most vulnerable species. But without action on emissions, she warns, even that may not be enough. The heat is arriving faster than evolution can answer it.
Carmen da Silva spends her days in the field with a butterfly net, chasing native bees from flower to flower across the continent—from Adelaide's suburbs to the rainforests near Cape York. As an evolutionary physiologist at Macquarie University's Pollinator Futures Research Centre, she has made it her work to understand which of Australia's native bees can survive what's coming.
The answer, it turns out, is complicated. It depends almost entirely on where a bee chooses to live.
Da Silva and her colleagues from universities across the country tested the heat tolerance of dozens of native bee species. What they found was counterintuitive: the bees that nest inside plant stems—living in the most exposed, least sheltered homes—are actually the most heat tolerant of all. Their bodies have evolved to withstand extreme temperatures. But this advantage becomes a liability in a warming world. When the heat arrives, stem-nesting bees have nowhere to retreat. They cannot burrow underground or hide in a hollow. They are trapped in their own homes.
The ground-nesting bees, by contrast, have a different problem and a different advantage. About 70 percent of Australia's native bees nest underground, and while their bodies are generally less heat tolerant than their stem-nesting cousins, they possess something more valuable: a cool refuge. When temperatures spike, they can retreat into the earth. The soil below the surface stays relatively cool even when the air above burns. This simple fact of geography may be the difference between survival and collapse.
But geography alone does not tell the whole story. Tropical bees—the species that live closest to the equator—are in the most precarious position of all. They have evolved to live near the upper limit of what their bodies can tolerate. There is no margin for error. As global temperatures rise, even small increases push them past the threshold of survival. The animals that live in the warmest places on Earth are the least able to adapt to a warming world.
Australia is home to more than 1,700 native bee species, and their work is essential. They pollinate the crops that feed people and the wild plants that hold ecosystems together. The stingless varieties, in particular, are critical pollinators for tropical fruits and nuts—macadamias, lychees, watermelons. Queensland's honeybee populations have been devastated by the varroa mite, a parasitic pest that has ravaged commercial hives. Native bees are now the backup system, the insurance policy for food production across the continent.
Da Silva emphasizes that native bees can adapt to climate change, but only across generations. Evolution works slowly. Individual bees cannot acclimatize to new conditions within their own lifetimes—they cannot learn to tolerate heat they were not born to handle. This means the window for action is narrow. Conservation efforts must focus on creating cool microclimates for the most vulnerable species, particularly in the tropics. But without action on emissions, even that may not be enough. The heat is coming faster than evolution can keep pace.
Citações Notáveis
Native bees can adapt to climate change over multiple generations but not within individual lifetimes through acclimatization.— Carmen da Silva, evolutionary physiologist, Macquarie University
It's really important that we have these native bees as backup pollinators.— Carmen da Silva
A Conversa do Hearth Outra perspectiva sobre a história
Why does nesting location matter so much for heat survival? It seems like it should be the bee's body that determines whether it lives or dies.
You'd think so, but the body and the home are inseparable. A stem-nesting bee's physiology is built for exposure—it can handle extreme heat because it has to. But that same bee has nowhere to hide when the temperature becomes unbearable. A ground-nesting bee's body is less tough, but it has a refuge. In a crisis, refuge matters more than toughness.
So the tropical bees are in trouble because they're already living at their limit?
Exactly. They've evolved to live in a narrow band of temperatures. There's no slack in the system. When the climate shifts even a few degrees, they're already past what they can handle. They can't move to a cooler place—they're already in the warmest place on Earth.
Can they evolve faster? Can natural selection speed up?
Not in the way we need. Evolution happens across generations, and bees live short lives. A bee born today cannot learn to tolerate heat it wasn't built for. Its offspring might be slightly more heat-tolerant, but we're talking about decades or centuries of change. The climate is changing in years.
What happens to agriculture if the native bees collapse?
We lose a critical pollinator. Honeybees are already struggling with disease. If native bees fail, particularly the stingless bees in the tropics, you're looking at reduced yields for macadamias, lychees, watermelons—crops that depend on them. It's not just about food. It's about the whole ecosystem falling apart.
So what can actually be done?
Create cool refuges where they can survive. Plant native vegetation that provides shade and moisture. Protect the places where ground-nesting bees can burrow. But honestly, without cutting emissions, you're just buying time.