Microscopic worms: biocontrol to protect SA's pine forests

AUGUST 24, 2016

The Sirex woodwasp (Sirex noctilo), is threatening South Africa’s pine forests, which makes up more than half of the 1.3 million hectares of plantation forests (trees planted to meet human demand for wood and wood products) in the country. This industry employs 170,000, and exports $1.7 billion worth of wood products annually.

The Forestry and Agricultural Biotechnology Institute (FABI) at the University of Pretoria has been working to combat Sirex woodwasp infestations. Together with industry and government partners, they have helped to control the infestations in South African pine forests. “Methods to control pests such as the Sirex woodwasp exist, but a solution that works elsewhere doesn’t always work as well here in South Africa as it does in Australia or Brazil,” advises research lead Professor Bernard Slippers. “It is essential that one finds local solutions that consider local forestry practices, genetic diversity and environment conditions.”

Discover more background behind the significance of the research on the globe’s pine forests  at www.researchmatters.up.ac.za.


The solution

Researchers at FABI are using microscopic worms called nematodes against Sirex in an approach known as biocontrol. “The nematodes infect wasp larvae, and eventually sterilize the adult females that develop from these larvae,” explains Professor Slippers. “A fungus that lives in symbiosis with the wasp plays a key role in this biological control approach, since the nematodes must feed and breed on this fungus to infect the wasp larvae.”

The Nematode lifecycle: 

The process is complex. By studying each organism’s genome (which is all the genetic information contained in its cells) and population, FABI can select and develop the best nematode and process for the job. For this purpose, the researchers are creating global maps of the natural distribution of different variants of nematodes, wasps and the fungus. The genomic information might one day even be used to create sterile male wasps, which might offer additional control options.


Impacting government and industry

FABI works in close partnership and regularly shares new findings with government and industry to help keep trees healthy. FABI, as a global front-runner in holistic tree health research, has called on world leaders to adopt a more integrated model to tackle similar problems on a global scale through international collaborations and multi-disciplinary research.


Discover the story in full at Research Matters, the University of Pretoria research website:










Credit: Ludwig Eksteen