South Africa’s forestry industry is huge. Pine and eucalyptus plantations in Kwa-Zulu-Natal and Mpumalanga alone contribute R12.3-billion to the country’s coffers each year and employ more than 340 000 people.
But what happens when a tiny, insidious alien arrives and starts boring holes in that all-important bottom- line, shaving off millions of rands and virtually levelling huge swaths of forest? And posing possible threats to our indigenous wild species?
Enter Professor Mike Wingfield, protector of South Africa’s commercial forests. He’s the first line of defence in the war against arboreal pests and diseases and the leader of a team of scientists at the Forestry and Agricultural Biotechnology Institute (Fabi), which took on the sirex woodwasp, Sirex noctilio, when it first moved to the major pine forest areas of South Africa.
Wingfield is the director of Fabi, a Mondi professor of forest protection, director of the Tree Protection Cooperative Programme — a Fabi programme — and the director of the department of science and technology and the National Research Foundation’s Centre of Excellence in Tree Health Biotechnology (CTHB).
All of which makes him pretty much one of the world’s fundis when it comes to understanding the origins and patterns of global movement of insect pests and pathogens of trees. And where sirex is concerned, he and his research team are the insect’s arch nemesis.
The sirex, or Eurasian woodwasp, bores holes in the soft wood of the forest pines, which grow well in South Africa’s warm climate. It’s not only the sirex larvae that kill, but also a symbiotic fungus that sirex carries — Amylostereum areolatum — which attacks the wood and rots it, in extreme cases destroying entire sections of forest.
‘Sirex first appeared here in 1990,” says Wingfield. ‘It is native to Europe where its natural predators keep it in check. But just over 100 years ago it began to spread, first to New Zealand and then to Australia and South America. Two years ago it appeared in New York in the United States, and is now known to be established in eastern North America,” says Wingfield. ‘In every country where it has become established it has caused considerable damage to commercial forests and cost to local economies.”
When sirex moved to the summer rainfall areas of South Africa, the Fabi team launched a programme of intensive research on this winged pest, working closely with researchers in Australia, New Zealand and South America.
To control sirex the Fabi team focused on various options and discovered that various biological control agents, such as a parasitic nematode called Deladenus siricidicola, which the Australians had developed, were ineffective in areas where the epidemic was most severe.
‘What we found is that biological control agents need to be tailored to the local strains of each pest, which is particularly complex,” says Wingfield.
He leads an extensive team, including a core of eight academics, that works closely with all major players in South Africa’s pulp and paper industry and which is trying to find a more effective biological control of sirex.
‘We are certain that our efforts this year will have a more positive impact than last year and that this will be a growing trend,” he says.
Sadly, the woodwasp is but one of a string of potentially lethal threats to South Africa’s commercial forests, some of which have been discovered only recently. One of these, the bronze bug, Thaumastocoris peregrinus, arrived in 2005 from its native Australia, where it was discovered only a few years ago.
‘It’s a massive threat,” says Wingfield. ‘Finding a biological control agent for it is going to be a core part of our next Thrip cycle.” The bronze bug is a sucker. It is small and resembles a Mirage fighter jet covered with spines. It attacks eucalyptus trees.
‘We know very little about the bronze bug, apart from the fact that it sticks to everything, multiplies rapidly and sucks the moisture out of leaves, which then drop,” says Wingfield.
‘In the year since it first appeared in South Africa it spread from the north of the country to Cape Town. What we now know is the same insect has invaded Argentina and it arrived in Uruguay last year. It has spread to Brazil and it reached Chile just weeks ago. This is a growing crisis in South America and the only positive point is that we can share the effort to fight the pest with others.”
Wingfield has dispatched a research team to Australia to look for biological control agents that can be used to fight the bronze bug. Perhaps the greatest aspect of Wingfield’s research is understanding and identifying the pathways tree pests and pathogens take — the way they spread.
‘In the bronze bug’s case, because it is so sticky, it is likely spread on people’s clothes and probably by birds,” says Wingfield. The rate at which serious pests have arrived on the tree scene in the past decade worries Wingfield.
‘We have seen an inordinate increase in the number of new threats,” he says. ‘The greatest power we have to fight tree pests and diseases lies in the outstanding researchers and students that form part of our team. This team is the envy of many forestry industries worldwide and the human capacity development that emerges from the Thrip programme is what makes it special,” says Wingfield.