Global War On Weevil Hots Up

Global War On Weevil Hots Up
24 January 2007

UK based researcher Dr Scott Johnson has been in New Zealand for the past six weeks finding out how to combat the clover root weevil in a warmer climate.

With temperatures in the United Kingdom predicted to rise over the next few decades he believes some of the techniques used in New Zealand may be useful there as global warming begins to take effect.

“Back home we only have one generation of these weevils breeding each year but in New Zealand you have two to three annually.”

While it is not a serious pest in the UK at present it is predicted that it could become a real problem for pastoral farmers as the climate in the UK changes.

Dr Johnson, who is a researcher at the Scottish Crop Research Institutein Dundee, has spent time at several AgResearch campuses, including a week at Lincoln near Christchurch and five weeks at AgResearch’s Ruakura Campus in Hamilton. AgResearch is leading the fight against clover root weevil in New Zealand through a biocontrol programme funded by Dairy InSight and Meat & Wool New Zealand.

First discovered in the Waikato in 1996, it is estimated that the clover root weevil could cost the pastoral sector up to $300 million per year.

The adult stage of clover root weevil feeds on clover leaves and the larval stages feed on clover roots. Young larvae tend to feed in clover root nodules (which capture atmospheric nitrogen), while bigger larvae will feed anywhere on the root system.

When clover quality is compromised, extra nitrogen fertiliser is required, and this can have negative economic and environmental impacts.

While temperatures have not been quite as warm as Dr Johnson expected, he says he has learnt a lot about controlling the pest including a scoping study and discussing possible areas of collaboration with clover root weevil experts at AgResearch.

ENDS

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