It’s an unusual title to aim for but Charleville can lay claim to being the coral cactus control capital of Australia, thanks to a tiny insect that’s been eating its way through the succulents of south west Queensland.
Following various trials, the cochineal bug, Dactylopius tomentosus, was released into the paddock at Longreach in April 2016 and then to various other places, including Eulo, in February 2017.
As the mealy bug, an import from South Africa, sucked the sap out of hectares of spiky cladodes from Hebel to Thargomindah, hope rose among land managers that the insect would be a useful tool that would allow graziers to use country productively again.
A lot of incubation and distribution work took place last year via the network of what was known as the South West NRM, giving rise to former staff member, Craig Alison, to say that Charleville was set up to be the coral cactus biocontrol centre of Australia.
After two years of biocontrol, Charleville became the biggest distribution agency in Queensland.
Some 11 tubs of infected coral cactus cladodes had been handed out to landholders at the start of the year, and five boxes of tiger pear, while three dozen boxes of coral cactus and one dozen boxes of tiger pear were released by SWNRM project officers.
The economics of letting the bugs loose were also appealing.
With one box of biocontrol servicing 25 infected cactus, and one 15l backpack spraying 25 decent-sized cactus, it has been estimated that it takes about $100 worth of mixed Access herbicide and diesel to do the same job as the bugs, using best practise weed management techniques.
As former project officer, Suzi Berry said, spraying was also restricted to weather and time of day.
“The bug works 24/7 and it doesn’t recognise fencelines or absentee landlords,” she said.
According to Agriculture Minister, Mark Furner, the insect had controlled coral cactus in a 120ha paddock within 21 months.
“An important aspect of the research showed that different populations of the cochineal attack different species of Cylindropuntia cactus, which allows for more effective targeting of infestations,” he said.
Suzi said cactus control was a 10 to 20 year plan.
“It’s not just kill the plant and that’s it.
“With biocontrol, if you can completely naturalise it, you don’t have to worry about spraying every plant because the bioagent will find them and significantly reduce them.
“You can spray live plants in a year’s time if the bug’s died off and there are some cactus left.
“It’s all about integrated management techniques.”
Current project officer, Lucas Mackie, said Southern Queensland NRM staff in the Charleville office were still able to assist with requests for batches of the control agent, providing enough notice was given.
