25 January 2002

Media Release
Farming Media & Daily Media Farm Pages

New wasp in fight against clover root weevil

Finding the right strain of a tiny wasp will be the key to solving farmers’ problems with the clover root weevil, say researchers.

Stephen Goldson, who leads the AgResearch bio-control and bio-security group at Lincoln, says the parasitoid wasp Microtonus aethiopoides has the potential to stop the weevil in its tracks – and it appears a new strain found in Europe will do just that.

In the last six years clover root weevil – a severe pest of white clover – has spread through the northern North Island and can now be found in pastures as far south as Te Kuiti. It has also been reported on the East Coast, near Ruatoria.

Two years ago a potentially suitable version of M. aethiopoides was found in Europe. But scientists were reluctant about releasing it here, because of the presence of a Kiwi strain of the same wasp which doesn’t attack clover root weevil.

Scientists suspected that if the two strains interbred, the European strain might have become ineffective.

However, a new strain found late last year doesn’t require males for breeding and seems to be effective in attacking clover root weevil.

"The fact that this wasp is able to make copies of herself means that her offspring will not be diluted by the male wasps here – and hopefully it will concentrate on reducing the impact of clover root weevil," Dr Goldson says.

Dr Goldson says the research team is now studying the wasp’s genetics, fertility, longevity, attack rates, development rates and host range. They will also make sure the wasp’s breeding behaviour is stable.

"We have to know what we’re dealing with, so we know any likely risks to the environment and non-target species."

AgResearch’s work into clover root weevil is jointly funded by WoolPro, Meat New Zealand, the New Zealand Dairy Board, the Game Industry Board, and the Foundation for Research, Science and Technology, as well as the Foundation for Arable Research, AGMARDT, the C. Alma Baker Trust and the Lincoln Foundation.


For more information, contact:

WoolPro research manager Ken Geenty,
tel 06 356 8611

AgResearch scientist Stephen Goldson,
tel 03 325 6900.


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