19 December 2001

Media Release
AgriBusiness media


New wasp in fight against clover root weevil


A new variety of wasp, introduced from Europe, could provide a solution to farmers’ problems with the clover root weevil.

The production-sapping weevil – a severe pest of white clover, has spread through the northern North Island in the last six years. It is now found in pastures as far south as Lake Taupo.

AgResearch’s Stephen Goldson, who leads the bio-control and bio-security group at Lincoln, says that progress is being made with a tiny parasitoid wasp, which has the potential to stop the weevil in its tracks.

A potentially suitable wasp called Microtonus aethiopoides was found in Europe two years ago. But researchers were concerned about it interbreeding with a kiwi strain of the same species, which doesn't attack clover root weevils here. It was feared that the kiwi strain might render the European wasp ineffective.

However, researchers’ interests were then lifted by another European wasp strain which doesn’t require males for breeding, and it still appears 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 work has now begun to examine the wasp’s genetics, fertility, longevity, attack rates, development rates and host range. Researchers will also make sure the wasp’s breeding behaviour is stable, before any release is likely.

"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.