Diagnostic characteristics and biology of three Microctonus spp. (Hymenoptera: Braconidae, Euphorinae) parasitoids of weevils (Coleoptera: Curculionidae) in New Zealand pasture and lucerne.

Abstract

Two species of Microctonus have been introduced to control 2 weevil pests found in the pastoral habitat. M. aethiopoides Loan was introduced and successfully controlled Sitona discoideus (Gyllenhal) while M. hyperodae Loan has been recently released to control Listronotus bonariensis (Kuschel). The third species, M. zealandicus Shaw, is indigenous to New Zealand and is associated with a native Curculionidae Irenimus aequalis Broun.

Microctonus aethiopoides has been found to parasitise field populations of L. bonariesis and I. aequalis, while laboratory observations have suggested that I. aequalis may be a target for opportunist parasitism by M. hyperodae. As the 3 weevil species may be found co-existing in the pastoral habitat, a diagnostic key and brief description of the biology is provided to discriminate between the 3 parasitoid species.

Keywords:

• Hymenopera
• Braconidae
• Microctonus spp
• parasitoids
• weevils
• New Zealand