Kangaroo Valley sustainability expert visits fireweed-killing aphid at Tilba

Interest in the fireweed killing-aphid found at Tilba is growing among South Coast farmers, while scientific work continues to identify and further study the mystery insect.

Former Shoalhaven farmer and founding member of the Kangaroo Valley Sustainable Farming Group, Robert Cochrane travelled 250km last weekend to visit the Tilba property of Ron Snape where the aphid was first spotted about two months ago.

Mr Cochrane brought with him his grandson Alastair Urquhart, a Year 7 Nowra Anglican College student, who has an interest in the control of fireweed and also earns extra money picking fireweed for Kangaroo Valley farmers.

The Shoalhaven visitors were very impressed with the impact of the aphid that has all but decimated the noxious fireweed on Mr Snape’s property and are calling on scientific experts to put more resources into identifying and studying the aphid.

“I’m excited and relieved to see that nature has sent a species along that is going to eradicate it,” Mr Cochrane said. “I’m so pleased but now more investigation needs to be done.”

Both Mr Cochrane and Mr Snape are disappointed with the initial response from the scientific community and want studies to be done to identify the aphid and how it can be carried over when the fireweed naturally declines during the hot summer months.

Mr Cochrane said the sustainable farming group was formed 36 years ago, about the same time that fireweed showed up on the South Coast. 

The group’s focus on controlling the fireweed through picking and other measures had played a significant role in limiting the weed’s impact, but even so there were today patches of weed on certain properties where control had been less than satisfactory. 

Scientists and weed experts initially downplayed the role the aphid could have in controlling fireweed but interest has grown since the impact the insect is having on fireweed has become obvious.

And the good news is that there have been further sightings of the black aphid at properties at Mystery Bay, Cobargo and even Tanja much further to the south. 

A spokesperson from the NSW Department of Primary Industries said the NSW DPI has made an initial identification of the aphid found at Tilba, with confirmation pending the arrival of fresh samples and molecular analysis.

The scientific community at the state and federal level however remain focussed on the official biological control agents in South Africa that evolved a natural predator of the weed in its native southern Africa.

The DPI and CSIRO are part of a collaborative biological control program to better manage fireweed at the University of KwaZulu-Natal (UKZN) in South Africa, the DPI spokesperson said.

NSW DPI Weed Research Unit leader, Dr Kerinne Harvey , was currently in South Africa working with UKZN research team.

“At this stage, several insects have been identified and are the focus of laboratory and field studies in South Africa as potential biocontrol agents on fireweed,” the spokesperson said.

“The team is developing ways to breed the prioritised agents, including a root feeding flea beetle and a stem-boring moth. Both these agents are in the process of having their identities confirmed through the Agricultural Research Council in Pretoria, South Africa.

“Researchers are examining their lifecycles and host ranges, as native range studies are imperative before import into Australian quarantine facilities can occur. If import is possible, further host specificity testing against native species and other economic species closely related to fireweed will occur.”

But Mr Cochrane and Mr Snape said regardless of the longer-term South African studies, they would like to see more resources and emphasis put on the mystery Tilba aphid. 

Mr Snape has made a personal crusade to have the aphid he found further studied, even going to the Eurobodalla Shire Council to plead for further studies, as well as his local state member.

Mr Cochrane has been working with Shoalhaven Council’s weed inspector, who last week was attending a state weed conference, and was going to spread the word about the aphid. He had also been in contact with his local state member, Gareth Ward to see if he could speed up research on the aphid.

He said he personally wanted the control of fireweed to be compulsory on private property as it had potential to and already was reducing stocking rates and could even kill livestock through liver damage.

Both men challenged the scientists from the DPI and CSIRO to come to the Tilba property.

“I would like the CSIRO to come down and see what impact the aphid is having and failing that there needs to be an independent investigation,” Mr Snape said.

“We don’t know when the South African beetle will be ready and it could be years yet, while the aphid is having this massive impact right now.”