Status of clover root weevil and its biocontrol agent in the South Island after six years.

Abstract

Clover root weevil was first discovered in the South Island in 2006. Since then its distribution has been monitored. Although not yet occurring throughout all the South Island, it is widespread and has become common in many regions. The first releases of a biocontrol agent, the Irish ecotype of the parasitoid wasp Microctonus aethiopoides, were also made in 2006, with more made as suitable weevil populations were detected. In all areas where the releases have been monitored the biocontrol agent has established and extensive natural spread has occurred from the earlier release sites. As a consequence it is now established extensively in the northern South Island. Targeted releases have established the agent in Canterbury, Otago and Southland. Keywords: Biocontrol, clover root weevil, Sitona lepidus, Microctonus aethiopoides