Caught by the SciBraai Eye

14 February 2014:

Despite our eternal reminder that Oscar Pistorius shot and killed girlfriend Reeva Steenkamp on Valentine’s day, South Africa’s anti-gun laws have been generally quite effective.  This story and those of a bullfrog and a weevil shook up the SciBraai Eye this week.


Great shakes, Grahamstown!

For starters, did you know that earthquakes can occur in the Grahamstown area of the Eastern Cape?

Well, for the years between 1820 and 1936, six at least did! In a study published in the journal Bulletin of Earthquake Engineering, five regional events that were felt in Grahamstown during that period are described, as well as one that was not.

The study was conducted by Paola Albini of the Instituto Nazionale di Geofisica e Vulcanologia in Italy, conjunction with Fleur Strasser and Nicolette S. Flint of the South African Council for Geosciences.

Reference: Albini, P. et al (2014). Earthquakes from 1820 to 1936 in Grahamstown and surroundings (Eastern Cape Province, South Africa), Bulletin of Earthquake Engineering


Artificial wetlands a saving grace for giant bullfrogs

Researchers from the University of the Witwatersrand spent quite a bit of time near the Total Petroport on the N14 in Gauteng recently to study whether the near threatened African bullfrogs (Pyxicephalus adspersus) indeed breed in the nearby artificial wetlands or not.

Many such wetlands have over the years been created in urban landscapes to counter the effect of urbanisation on our biodiversity caused by habitat fragmentation and transformation. Little is known about the specific habitat requirements of frog species for breeding.

The study was conducted in the Total Petroport N14 Biodiversity Reserve, which is an artificial wetland complex created in 2006 specifically for the conservation of bullfrog populations.

It was found that bullfrogs are non-selective in their choice of breeding sites, and their breeding success appears to largely depend on stochastic events, such as the drying up of pans. Confounding factors such as proximity to human activity may also impact breeding success.

“We conclude that a wide variety of artificial pans can adequately ameliorate negative impacts of land transformation on bullfrog recruitment,” writes Ryan Thomas in an article published in the African Journal of Herpetology.

Reference: Thomas, R. et al (2014). Restoring breeding habitat for Giant Bullfrogs (Pyxicephalus adspersus) in South Africa, African Journal of Herpetology


Firearms Control Act saves lives

More than 4500 lives of people living in five South African cities have been effectively saved thanks to South Africa’s Firearms Control Act (FCA) passed in 2000.

So says researchers from the University of Cape Town, the Medical Research Council and the University of Washington who assessed the effectiveness of the FCA through a study published in American Journal of Public Health. They compared firearm homicide rates with rates of nonfirearm murders across five South African cities from 2001 to 2005. Their retrospective population-based study included 37 067 firearm and nonfirearm homicide cases in Cape Town, Durban, Johannesburg, Port Elizabeth, and Pretoria.

A significant decreasing trend in firearm homicides was found since 2001. The researchers estimate that at least 4585 lives were saved in the process.

“With the revisiting of the gun control debate both in South Africa following the high-profile shooting incident involving celebrity paralympian, Oscar Pistorius, and in the United States after recent killings at Newtown, Connecticut, it is instructive to assess the impact of stricter gun control applied in South Africa through the FCA,” writes lead author Richard Matzopoulos of the University of Cape Town and the Medical Research Council.

“Stricter gun control mediated by the FCA accounted for a significant decrease in homicides overall, and firearm homicides in particular, during the study period,” Matzopoulus adds.

Reference: Matzopoulus, R.G. et al (2014). Firearm and Nonfirearm Homicides in 5 South African Cities: A Retrospective Population-Based Study, American Journal of Public Health


Zapping banded weevils before they head to Europe

The banded fruit weevil (Phlyctinus callosus) is a pest that has given more than one exporter of South African fruit to United States and Europe a major headache. Because it does not occur in these countries, the only option is to first disinfect all produce with methyl bromide to ensure that no weevil sneaks in.

Now entomologists Andries Duvenhage and Shelley Johnstone of Stellenbosch University have tested a more sustainable alternative: irradiation treatment of whole pallets of packed fruit. In the process, all insects that may be hiding within the cartons are sterilized. Trials were conducted during the 2009‐2010 and 2010‐2011 fruit harvesting seasons. Results of their successful efforts were published in the Journal of Economic Entomology.

Reference: Duvenage, A. J. & Johnson, S.A. (2014). The Potential of Irradiation as a Postharvest Disinfestation Treatment Against Phlyctinus callosus (Coleoptera: Curculionidae), Journal of Economic Entomology

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