Agricultural
8 October, 2025
‘Weevil Kinevil’ answer to wicked weed?
A team of world-leading researchers from CSIRO is exploring if a small insect, the stem-boring weevil, Lixus caudiger, could hold the key to tackling flaxleaf fleabane; one of the most invasive and costly weeds in Australian grain production.
Prior CSIRO research has noted that across the Darling Downs, flaxleaf fleabane (Erigeron bonariensis) is among the weed species that is becoming increasingly resistant to glyphosate and presenting management challenges both on roadsides and in adjacent agricultural land.
This weed is estimated to cause revenue losses in excess of $43 million for grain producers.
The research, an investment by the Grains Research and Development Corporation (GRDC), aims to deliver biological control solutions for fleabane, a weed that costs Australian growers significantly each year in lost yields and control costs.
CSIRO is working closely with international collaborators in Brazil and France to identify and test fleabane’s natural enemies, and the weevil which is native to South America has shown promising results from early trials.
This specific weevil feeds on fleabane leaves and stems, while its larvae burrow inside the stem tissue, hollowing out plant structures and weakening them until they collapse.
The internal feeding often prevents the weed from flowering and setting seed, cutting into the weed’s ability to spread.
The colony of weevils, housed in CSIRO’s quarantine facilities, is undergoing further testing, with researchers carefully monitoring feeding, mating, egg-laying and larval development across a wide range of test plants.
If the insect proves safe and effective, CSIRO will prepare submissions for regulatory approval before any field release.
CSIRO Principal Research Scientist, Dr Michelle Rafter said her team researching the weevil was witnessing promising signs that Lixus caudiger is highly specialised to fleabane, while not causing any damage to the crops themselves.
“So far, our testing shows the weevil is restricted to fleabane and its close relatives,” Dr Rafter said.
“That’s exactly what we want in a biocontrol agent, something that hones in on the target weed without threatening native plants or crops.
Flaxleaf fleabane flourishes in non-cropped areas like fence lines and roadsides, sending clouds of wind-borne seed back into cropping paddocks.
