RESEARCH

Dazed by the light

IN 2014, WITS Professor of Entomology, Professor Marcus Byrne (PhD 1998) in the School of Animal, Plant and Environmental Sciences, was part of an international team that discovered dung beetles use the stars to orientate themselves.

This year, Professor Byrne and his team, involving scientists from the University of Würzburg in Germany, and Lund University in Sweden, found that South African dung beetles (Scarabaeus satyrus) are unable to use their star compass under a light-polluted sky. The findings of this research were published in the journal Current Biology.

To test how light pollution affects dung beetles’ ability to orientate themselves, Professor Byrne and team conducted experiments in which they measured how two sets of dung beetles chose to orientate themselves on the same night, under different conditions. One under the bright city lights of central Johannesburg, and one in a rural part of Limpopo province under a much more natural sky where the stars are not obscured by skyglow.

The team found that under light-polluted skies, dung beetles move towards bright artificial light sources such as streetlights or lights from buildings, rather than a destination they might otherwise choose when guided by the stars.

In addition, beetles that viewed direct light pollution behaved unnaturally, but were still oriented. But those that viewed light-polluted skies without brightly lit buildings were completely disoriented. “We just need to switch off the lights. We need to be thoughtful about how we use this wonderful invention of ours, and we can reduce the effects that light pollution has on the world around us,” says Professor Byrne.

Image: Shivan Parusnath

High carbon dioxide levels stunt growth

A new study led by Wits University post-doctoral researcher, Dr Claudia Tocco, provides evidence that elevated CO2 levels directly affect the development and survival of tunnelling dung beetles (Euoniticellus intermedius). The study, published in the international journal, Global Change Biology, found beetles grown under heightened levels of atmospheric CO2 experienced lower survival rates, and were smaller in size. 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. Further studies will tease out whether it is the CO2 levels in the dung ball, the brood balls, or the soil in general that is affecting dung beetle development.

A new study led by Wits University post-doctoral researcher, Dr Claudia Tocco, provides evidence that elevated CO2 levels directly affect the development and survival of tunnelling dung beetles (Euoniticellus intermedius).

The study, published in the international journal, Global Change Biology, found beetles grown under heightened levels of atmospheric CO2 experienced lower survival rates, and were smaller in size. 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. Further studies will tease out whether it is the CO2 levels in the dung ball, the brood balls, or the soil in general that is affecting dung beetle development.