Tropical grass webworm (Herpetogramma licarsisalis): implications for dairy farming in Northland

摘要

The presence of larvae of Herpetogramma licarsisalis (tropical grass webworm (TGW)) in pasture on the Aupouri Peninsula in Northland, New Zealand, was confirmed in March 1999. A delineation survey undertaken in late March 1999 found an infested areaof approximately 37 000 ha, of which 4450 ha was in dairying. The establishment of TGW in the area has been confirmed by ongoing monitoring of populations from 1999 to the present. Populations decline to extremely low numbers over the winter months withthe main pasture damage period in early autumn (March/April). Infestations to date have been mainly confined to kikuyu pastures. In 1999 and 2002 visual estimations were made of pasture damage by TGW. The implications of this damage are discussed withinthe context of management practices and economic constraints for dairy farming in the area.