A beetle smaller than a sesame seed is killing huge trees throughout South Africa, and little can be done to stop it.
The polyphagous shot hole borer, a native of southeast Asia no bigger than 2mm, has found its way to South Africa and is infesting trees at an alarming rate.
According to Professor Marcus Byrne, an Ig Nobel prize winner and entomologist at the University of the Witwatersrand, the beetle bores tunnels into tree trunks where it spreads the fungus Fusarium euwallaceae, which effectively cuts off the trees’ vascular system, causing them to die. “It’s an ambrosia beetle, which means it carries a fungus which it feeds its babies on.
When it introduces that fungus into trees that have never experienced it before, it threatens those trees with illness or death.”
Byrne says no one truly knows how the beetles made their way to South Africa.
“We happen to be a very connected world and trade today allows for the movement of goods all around the world. We’re not very good at screening these animals that hitchhike around the world on our consumer goods.”
According to Byrne, there isn’t a solution to rid trees of these beetles once infested.
“You can apply a fungicide, but the scale at which you would have to apply it is just ridiculous.
“There are lots of snake-oil merchants that are trying to sell what they see as solutions, but none of these works.”
The local beetle infestation was first noticed last year by Dr Trudy Paap — a postdoctoral fellow at the Forestry and Agricultural Biotechnology Institute at the University of Pretoria — in the KwaZulu-Natal National Botanical Garden in Pietermaritzburg, and it has since been found nationwide, including in Johannesburg and as far as the Northern Cape.
Johannesburg has what is considered one of the world’s largest urban forests with an estimated 10 million trees.
According to Andrea Rosen, co-director of the Johannesburg Urban Forest Alliance, up to 100 000 trees in Johannesburg could already be infested, and the infestation is spreading fast.
“The polyphagous shot hole borer is of grave concern,” Rosen said on Tuesday.
“Some projections go up to half a million trees that are affected in Johannesburg alone, which is a substantial part of our urban forest canopy.”
Rosen says there is no effective treatment for infested trees apart from cutting them down and chipping the wood or burning it.
A local company, Pan African Farms, has developed a solution that has shown to be effective in laboratory conditions but is pending emergency registration before it can be used on actual trees. Rosen hopes that it will be available within the next two months.
According to Rosen, many trees in Johannesburg residents’ gardens could be infested without them knowing about it. —News24