Climate Change Is Stressing Bees
Excerpted from: Want to see how climate change is stressing bees?
The plight of the bumble bee has been well documented. In recent years, researchers
have reported worrying population declines across North America. Climate change
menaces these fuzzy insects.
But scientists have been limited in their ability to pinpoint what has stressed bumble bee
populations in the past, and what factors will imperil them in the future.
In an August issue of The Journal of Animal Ecology, a team of British researchers found
that 4 bumblebee species they studied appear to have become increasingly stressed by
climate change over the past century.
The stress appeared higher in the latter half of the century, they found, tracking with rising
global temperatures and more frequent extreme weather.
The scientists measured the wings of thousands of bumble bee specimens
collected over more than 100 years and housed in a network of natural history museums.
Using digital cameras and special software, they looked for subtle asymmetries in the wing
structure — a signal of environmental stressors that could affect bee growth and reproduction.
Scientists then compared their findings with historical climate data to find out if harsh weather
may have made life harder for the insects. The hotter and wetter the weather, the more likely
the bees were to grow lopsided wings, according to the researchers.
The conclusions suggest that bees could face mounting threats as weather worsens and
governments struggle to curb carbon emissions that fuel climate change. The prospect of
bee numbers plummeting further is a major concern because the insects play a key role in
pollinating wildflowers and crops, including staples such as tomatoes, potatoes and peppers.
The research team chose to look at bumble bee wing shapes because a previous body of
research showed that other organisms — not just bees but butterflies, lizards and rodents —
can grow asymmetrically when they experience environmental stress. The phenomenon is
called fluctuating asymmetry, and it has been observed in some animals when
they’re exposed to temperature changes, pesticides, infections and other hazards.
The bees’ wings in particular were useful to the researchers because they could examine the
museum specimens without damaging them.
The key thing really is that there is a way to measure bumble bees’ stress, at least comparatively.
This opens the possibility to compare populations, and potentially different species, to decide
which to focus conservation efforts on in the future.
This is critical for predictive modeling into the future, to target conservation efforts, and to understand
which species are most at risk, and subsequently which plants and crops that they pollinate are at risk
Bumble bee populations have dropped throughout the United States and Europe as Earth has heated
up. Research from 2020 found that the number of areas populated by the insects had fallen 46% in
North America and 17% in Europe.
Places with steep declines also experienced dramatic swings in climate, including higher temperatures
and more intense heat waves.
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