Clawing back a critically endangered ancient weevil from the brink of extinction is the goal of a new trial run by DOC.
The Canterbury knobbled weevil is one of New Zealand’s rarest beetles, and is known to be genetically ancient, or a ‘living fossil’. Thought to be extinct, in 2004 a small population was discovered in Burkes Pass, near Takapō/Tekapo.
After another small pocket of weevils was found in Mid-Canterbury late in 2024, DOC scientists hatched a plan with Te Rūnunga o Arowhenua to attempt to raise the rare beetles in captivity.
DOC Senior Science Advisor Tara Murray says the first hurdle for the endangered critters was survival in lab conditions.
“We started with just a few in a specialist lab, working with an amazing weevil specialist Barbara Barratt at the Bioeconomy Science Institute at Invermay,” says Tara.
“It was fairly experimental, feeding them all kinds of interesting things, including carrot chunks! They were easier to breed than we expected and quite hardy. We began with six and now we have more than 200 which is cool,” she says.
Tara says the team have now released the weevils back into Ōtūwharekai/ Ashburton lakes area in a trial to see how they fare.
“We’ve found a good spot with Aciphylla plants (taramea/spear grasses), which are a favourite of knobbled weevils.”
One of the reasons for the species’ decline is the removal of spear grasses from landscapes, which means the weevils lose their habitat.
“The release has gone really well, it’s amazing seeing them scuttle down into the depths of the spear grass to find a new home,” says Tara.
“What we’ve done here is a ‘soft release’, starting with protective covers over the plants. We’ll monitor how the weevils are doing and remove the covers in a week or so.”
Tara says it’s incredibly satisfying to be able to release the weevils back into an area they once would’ve thrived in.
“The Ōtūwharekai/Ashburton Lakes is a special place in terms of conservation and is very significant to Te Rūnanga o Arowhenua. They are our partners in this project, and we are all invested in the survival of this species and the protection of the land around it,” she says.
Pending the results of the soft release trial, plans will be developed with Te Rūnanga o Arowhenua to collect more wild weevils to be used in a full-scale attempt at establishing new populations so the rare beetles are not all in one place and at risk of being wiped out completely due to fires or other natural hazards.
Monitoring at Burkes Pass will continue so any weevils detected can be brought into the captive rearing facility to begin trying to boost the small population there.
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