The potential economic impact of the polyphagous shot hole borer in South Africa amounts to a whopping R275 billion over the next ten years, and municipalities will have to withstand the most of this cost if nothing is done to stem the tide.
The shot hole borer was first detected in South Africa in 2012 and has since spread to eight of South Africa’s nine provinces, making it the largest current outbreak of this invasive pest globally. Whereas most of South Africa most notorious invasive species are problematic in rural areas, this aggressive invader will have the largest impact on trees in urban areas.
This estimate is the result of a collaboration between economists at the Stellenbosch University (SU) School for Public Leadership and ecologists at the DSI-NRF Centre of Excellence for Invasion Biology (CIB) at SU, SU’s Department of Conservation Ecology and Entomology and the Forestry and Agricultural Biotechnology Institute at the University of Pretoria. Instead of basing their findings on existing data, the team used a modelling approach based on forecasted impacts – thus seeking to simulate possible future impacts of this invader if nothing is done to prevent it from spreading further.
The findings were published in the article “An assessment of the potential economic impacts of the invasive polyphagous shot hole borer (Coleoptera Curculionidae) in South Africa” in the Journal of Economic Entomology this week.
Prof Francois Roets, an ecologist in SU’s Department of Conservation Ecology and Entomology and one of the co-authors, says a tree-rich town like Stellenbosch stands to lose 20 000 of the big old oaks and plane trees lining its streets. In Somerset West, where the shot hole borer was first detected four years ago, more than 10 000 trees have already been infected and some of the oak trees are now dying.
He says urban trees are more susceptible to succumb to the beetle’s effects as these trees are usually already under stress in an urban environment compared to those in a natural forest rich with biodiversity. People in urban areas also tend to plant more non-native tree species – many of which are cloned and lack the genetic diversity necessary to fight off novel pests.The full article is for subscribed members only. To view the full article please subscribe. It’s FREE!Log In Register
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