Increased CO2 in the atmosphere makes dung beetles smaller

Date:
September 7, 2021
Source:
University of the Witwatersrand
Summary:
A new study has found surprising results that show that increased
levels of carbon dioxide (CO2) in the air can negatively affect
the survival and size of dung beetles.



FULL STORY ========================================================================== Climate change is a truth of the 21st century that is difficult to
avoid. The burning of fossil fuels in industry, for transport, and other everyday life activities of Homo sapiens has resulted in elevated levels
of CO2 in the Earth's atmosphere. Extreme weather conditions as seen
in recent flood, drought and fire events worldwide are some of the most
obvious ways in which increasing CO2levels are changing our world. But
there are some serious effects that CO2is having on our ecosystems that
are less easily observed.


==========================================================================
A new study led by Wits University post-doctoral researcher, Dr Claudia
Tocco, provides evidence that elevated CO2levels directly affects the development and survival of tunnelling dung beetles (Euoniticellus intermedius). The study, published in the international journal, Global
Change Biology, presents a possible explanation for the current 'insect apocalypse' -- a global decline in insect populations that is still not
well understood.

Serendipitous science "The idea to investigate the effects of elevated
CO2 levels on dung beetles was a result of 'serendipitous science',"
says Tocco. "My labmate and colleague at Wits, Mr Nic Venter, was growing
cacti under different CO2 conditions to investigate how these plants
may be affected under future scenarios in our changing world." Venter
was looking at CO2 levels under four scenarios: pre- industrial (~1750), modern-day, 30 years into the future, and 50 years into the future. "We thought, why not put some dung beetles under the same conditions and see
what happens?," says Prof. Marcus Byrne, senior author of the paper and
Dr Tocco's postdoctoral advisor. What they found came as a surprise.

Beetles grown under heightened levels of atmospheric CO2 experienced lower survival rates, and were smaller in size. "When raised under CO2levels predicted for the year 2070, a third fewer beetles emerged and were 14%
smaller in size when compared to pre-industrial CO2levels," says Tocco.

"When we first found this result, we were surprised!," says Byrne. "We
were not expecting such a drastic effect. In fact, we were not convinced
at first that this result was real, and so we repeated the experiment --
but we kept getting the same result." "We knew that increased CO2 levels
can affect insects indirectly by changing plant quality," says Venter,
"but did not expect such a direct effect on the beetles themselves."
The proof is in the soil


========================================================================== "Dung beetles like many insects, spend a large portion of their lives
in the soil -- as larvae, pupae and as adults," says Dr Blair Cowie,
another of Tocco's colleagues and fellow labmate in Prof. Byrne's
research group. "Most people perhaps do not realise that increases in atmospheric CO2 levels also affect the soil, and our study shows that
this can in turn affect animals that live in soil." The team suspects
that the negative effects experienced by dung beetles under scenarios of heightened CO2 in this study may be a result of increased competition
between the beetles and bacteria in the soil. "Our next steps are
to conduct further experiments to tease apart whether it is the CO2
levels in the dung ball, the brood balls, or the soil in general that
is affecting dung beetle development," says Cowie.

"It is the fact that the lives of dung beetles are so closely tied with
the soil that makes them such excellent model organisms to investigate
changes in soil ecology," says Tocco. "If atmospheric CO2 is affecting
dung beetles, it is affecting other insects too." Explaining the
insect apocalypse The findings from this study may provide new insight
into the cause of global insect declines. So far, other explanations
put forth have been questionable, and there are no universally accepted justifications. Changes in climatic conditions vary across the globe, and
some temperature changes may in fact be beneficial to insects. The use of insecticides is also patchy, and not ubiquitous across the planet. "Our findings of how heightened CO2 levels affect dung beetles presents a
plausible explanation for the insect apocalypse, since the increases in
CO2 are consistent across the planet," says Tocco.

These new findings are hot off the heels of another recent
breakthrough finding by Byrne and team, in which they found that light pollution negatively affects the ability of dung beetles to orientate themselves. "Whereas a solution to light pollution is easy -- we just
have to switch off our lights -- the CO2 problem is a bigger battle
to fight," says Byrne. "We need to seriously support the movement away
from fossil fuels, and invest in renewable energy -- or else we stand to
lose the vital ecosystem services that insects provide us free of charge." ========================================================================== Story Source: Materials provided by University_of_the_Witwatersrand. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Claudia Tocco, James Foster, Nic Venter, Blair Cowie, Danica Marlin,
Marcus Byrne. Elevated atmospheric CO 2 adversely affects a dung
beetle's development: Another potential driver of decline in
insect numbers? Global Change Biology, 2021; 27 (19): 4592 DOI:
10.1111/gcb.15804 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210907110627.htm

--- up 5 days, 8 hours, 25 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)