Otago Regional Council considers using RHDV to control rabbits

There are three strains of the rabbit calicivirus, known as Rabbit Haemorrhagic Disease Virus (RHDV), in New Zealand. Photo / ODT file

Otago regional councillors have asked staff to look into the possibility of removing an introduced virus, fatal to rabbits, off a national unwanted organisms list.

Removing red tape might allow the introduction of new strains of the rabbit calicivirus into some areas to spark new epidemics among Otago’s rabbit populations, councillors heard from a Manaaki Whenua-Landcare Research rabbit specialist.

Last week, councillors heard from three specialist consultants about rabbit monitoring and control in the region at a meeting of the environmental implementation committee.

Cr Gary Kelliher zeroed in on the advice of Landcare Research senior researcher Janine Duckworth, who endorsed the idea.

Kelliher said he wanted staff to pursue Duckworth’s advice to the extent they could reach an informed position as to whether it could be followed.

He did not want staff to go to such lengths that the investigation needed to be included in the council’s annual plan.

The reason he was “so interested” in the suggestion was because of the number of calls he was getting around rabbits in “peri-urban” areas, where an urban area adjoins a rural area.

There were “very limited tools” for rabbit control in peri-urban areas, he said.

“Everything we do kills cats as well - this doesn’t kill cats.”

There are three strains of the rabbit calicivirus, known as rabbit haemorrhagic disease virus (RHDV), in New Zealand.

First to arrive, RHDV1 was illegally released in Central Otago in 1997.

Then, in 2018, the regional council was part of a group that successfully applied to import and release RHDV1 K5, a Korean variant of the first strain.

By the end of that year, though, another virus RHDV 2 was detected in wild rabbits.

Duckworth said antibody testing was available that could show the prevalence of antibodies for different strains in rabbit populations.

RHDV1 was still persisting, but RHDV2 had become very common as well, she said.

At the moment rabbit control programmes could not take an existing strain of the rabbit virus within New Zealand and spread it elsewhere in the country.

A virus introduced anywhere had to be a product taken through Agricultural Compounds and Veterinary Medicines Act processes, she said.

“That’s because RHDV is still an unwanted organism - yet it’s endemic. It’s everywhere, but it’s still an unwanted organism.

It needed to be an unwanted organism otherwise new strains could come “willy-nilly” into the country, she said.

“But within the country, there is an opportunity to explore with MPI [Ministry for Primary Industries] whether it can be removed from the unwanted organisms list.

“And then you might be able to find a new way to cause epidemics, which is within the guidelines that MPI have for RHDV.”

Cr Kevin Malcolm said the council had engaged environmental consultants on the issue of controlling pest rabbits in the region and the advice that came back was “if we want to get serious about the removal of rabbits” some effort could be required to get the rabbit virus off the list of unwanted organisms.

“Surely, to me, if we’re actually serious about doing this, it would make good sense to do that.”

The council, last year, commissioned two reports into council rabbit monitoring methods and tools, to provide recommendations for improvement.

Those reports by Kurahaupo Consulting director John Parkes and Place Group environmental planning environmental consultant Hannah Palmer resulted in changes to night count and rabbit density monitoring, an end to the collection of immunity data, and the implementation of fly trap monitoring, next year, to collect virological data to track RHDV within an area.