A study published in Nature Communications assessed the heat tolerance of 95 native bee species in eastern mainland Australia. The research indicates that bees nesting in plant stems have a lower capacity to escape extreme temperatures compared to ground-nesting bees, making them more vulnerable to climate change in the near term.
Study Details and Methodology
- The research was conducted by scientists from Macquarie University, The University of Sydney, La Trobe University, Flinders University, University of Wollongong, Adelaide University, and The University of Queensland.
- Researchers collected bees from locations spanning Adelaide to Cape York in far north Queensland.
- Bee nesting behaviors were categorized into three types: ground burrows, wood cavities, and plant stems.
- Approximately 70% of bee species nest underground.
Key Findings
Heat Tolerance and Vulnerability: The study found that bees nesting in plant stems exhibited the highest heat tolerance. However, because their nests offer limited insulation and no cool refuge during heatwaves, these species are projected to be the most vulnerable to climate change.
Ground-Nesting Species: Ground-nesting bees generally have lower heat tolerance but can escape extreme heat by remaining in cooler conditions underground.
Tropical Species: Tropical bees were identified as facing the highest overall risk from climate change, as they already live near their thermal limits.
Evolution: The researchers confirmed that heat tolerance can evolve in native bees over multiple generations, but not through phenotypic plasticity (acclimatization within a single lifetime).
Reassessment of Risk: The study concluded that using microclimate temperatures instead of ambient air temperatures reverses vulnerability predictions, identifying stem-nesting bees as most at risk.
"Stem-nesting species appear to have the lowest capacity to escape unfavorable environmental temperatures and are likely to be most impacted by anthropogenic climate change in the near term." — Dr. Carmen da Silva, Macquarie University
Background
Australia has approximately 1,700 native bee species. Native bees are critical pollinators for ecosystems and crops, including macadamia nuts, avocados, mangos, lychees, and watermelons.
Researcher Statements
- Dr. Vanessa Kellermann (La Trobe University) stated that predicting which species will be vulnerable to climate change is a major challenge, and that high heat tolerance does not guarantee safety.
- Dr. Ros Gloag (University of Sydney) stated that understanding native bee behavior is key to identifying the greatest threats to their wild populations.
Implications
The authors recommended conservation measures, including halting land clearing in tropical forests, creating cool microclimates for sensitive species, and reducing greenhouse gas emissions to protect bee populations and pollination services.