A new study shows how climate change has been affecting the decline of bumblebee populations and posing risks to the crucial role of pollinators in the maintenance of plants and food all over the world.
(Photo : Pexels / Thijs van der Weide)
Temperatures For Thriving
Similar to humans, the bodies of bumblebees are best at thriving in particular thresholds of temperature. According to 180 years' worth of literature, Peter Levan, an environmental science professor from the University of Guelph, and his team were able to find that these insects can survive up to temperatures of 36 degrees Celsius. Such an optimal range of temperature for development lies at 30 to 32 degrees Celsius, which may vary from species to species.
Bumblebees are capable of thermoregulation. This means that they can control, to a certain extent, the heat within their bodies. However, according to Kevan, such a skill is not sufficient when it comes to the larvae that depend on them for growth and their nests.
For bumblebee nests, the optimal range of temperature sits between 82.4 and 89.6 degrees Fahrenheit. When heat goes up just slightly beyond 95 degrees Fahrenheit, this becomes lethal, even though bumblebees have the remarkable ability for thermoregulation.
Kevan explains that they can surmise that temperatures of nests that exceed the mid-30s mark would end up being detrimental and that temperatures that exceed 35 degrees Celsius would lead to death quite quickly.
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Climate Change Effects on Bumblebee Populations
In the recent decades, average temperatures all over the world have been rising significantly. Last year was the record-topped in terms of heat, while this year has been full of back-to-back extremes. Such a situation could get worse as fossil fuel burning persists and results in gas emissions that trap heat from the sun and amplify temperature rises.
Kevan explains that temperatures that are excessively high could become more harmful to the majority of animals and plants compared to temperatures that are cooler. During such cool conditions, organisms that do not regulate their own body temperatures metabolically could simply slow down. However, when temperatures rise too high, the metabolic processes begin to break down and cease. This quickly ensues death.
While climate change appears to play a crucial factor, there are also other factors in play. Pesticides, habitat loss, wildflower loss, and diseases are also contributors.
All over the world, there are over 250 bumblebee species with 49 of them being present in the US alone. In the past years, there have been two bumblebee species that have gone extinct.
The team of Kevan discovered that heat appears to be hard for these insects to adapt to. This results in dangerous heat stress for them.
With the case of bumblebees, when one insect finds it detrimental, this could end up becoming detrimental to all. The recently published study "Thermodynamics, thermal performance and climate change: temperature regimes for bumblebee (Bombus spp.) colonies as examples of superorganisms" shows that colonies of bumblebees are superorganisms wherein general survical is collective and dependent on the ability of the colony to generally produce offspring. In essence, though some bumblebees can take the heat, those that cannot end up posing a threat to the future of the colony. Moreover, if it is extremely hot, baby bumblebees end up dying before they could even get past the larval stage.
The study notes that too much heat is a major issue faced by most bumblebee species. It is also the factor that is thought of in most detail when it comes to global warming effects.
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