Potential for biocontrol of Sitona lepidus Gyllenhal by Microctonus spp.

Abstract

Laboratory experiments were carried out to determine whether either of the two braconid parasitoids Microctonus aethiopoides Loan or Microctonus hyperodae Loan, already established in New Zealand, would parasitise the recently introduced clover root weevil, Sitona lepidus Gyllenhal. No parasitism by either parasitoid was recorded in two no-choice experiments. In a third experiment, M. aethiopoides was exposed to S. lepidus and S. discoideus in either choice or no-choice cages. In this case, a very low level of parasitism of S. lepidus (1%) occurred in no-choice cages, but this was increased to about 6% in cages where both weevil species were present. It was concluded that neither parasitoid was likely to be a suitable biological control agent for S. lepidus.