HOLD CHISEL: Dr Helen Nahrung takes a chisel to a pine tree.
HOLD CHISEL: Dr Helen Nahrung takes a chisel to a pine tree. Picasa

Helen’s pines near home

IF the Gympie region feels just like home to visiting timber industry entomologist, Helen Nahrung, there is probably a reason for that.

Dr Nahrung is visiting at least the fringes of her old stomping grounds as she works to save Gympie's historically significant pine plantation industry from what may be one of its greatest pest threats yet.

The James Nash State High School graduate, whose family came from the Miva district, did her first forestry studies at Gympie's former Fraser Rd research station.

Now, she is working with the University of the Sunshine Coast on biological control experiments to protect Gympie from a tiny but significant threat, the sirex wood wasp.

As she puts it, she is trying to keep our industry one step ahead of the wasp, which came from Eurasia to New Zealand in 1900, arrived in Tasmania in 1952 and hit the mainland in 1960.

"It crossed the southern Queensland border in 2009 but so far has only been found in the pine forests of the Stanthorpe region."

How much of a threat it is to the Gympie region's hybrid pine plantations is a big and scary unknown. The other unknown is whether existing control methods will work here in the sub-tropics.

"The main threat is when there is a big outbreak, as there was in the 'Green Triangle' of Victoria and South Australia.

"It killed five million trees and did about $12 million damage," she said.

"Outbreaks occur when there are stressed trees, but if there are big enough numbers of wasps they will attack healthy ones, too," she said.

Once that happens, the trees don't stay healthy for very long.

The wasps have a symbiotic relationship with a fungus. They bore into a tree and inject venom and digestive liquid and the fungus kills the tree and attacks the timber. The wasp larve eat wood pre-digested by the fungus.

One important remedy is a biological control strategy involving a nematode which is commercially bred to fight the wasp.

"If the wasp can adapt to the different pine trees and the warmer, moister climate, it is only a matter of time before it is here.

"We need to know if it is a threat in this climate and if it is, whether the biological control measures we have in place will work.

"We're doing pre-emptive research to make sure we have a biological control agent when it arrives.

"The nematodes eat the wasp larvae. There are a few different strains of nematod, so it is a matter of finding the one that performs best here."