The larvae of this pest can devastate pasture by eating the clover root and killing the plant. The adults feed on white clover leaves producing a characteristic ‘notching’ of the leaf margin. Up to 1500 weevil larvae per square metre were counted in the soils underneath Waikato pastures in 1997, and this dramatically reduced clover content.

AgResearch scientists have released a tiny wasp from Ireland as a biological control agent for CRW. The wasp has been used successfully in the North Island to control this pest. The wasp lays its eggs in the weevil, thereby making it sterile. However, it is important more is understood about the distribution of CRW on the Taieri before we consider how we tackle the pest in the area.

Clover root weevil, Sitona lepidus, was first discovered in 1996 in Waikato and Auckland, and by 2004 it had spread throughout the North Island. In April 2006, AgResearch found a large population of CRW established in dairy pasture at Richmond, near Nelson, and it has been detected at Clinton. “The arrival of the weevil on the Taieri Plain is disappointing but inevitable” said Dr Barbara Barratt.

Farmers who identify CRW damage on their properties should contact Colin Ferguson at colin.ferguson@agresearch.co.nz

For more information contact:

Sam Fisher
AgResearch Media Liaison
021 714209

Colin Ferguson
AgResearch Scientist
03 489 9051

Dr Barbara Barratt
AgResearch Principal Scientist
03 489 9059