Sirex noctilio woodwasp in Australia: a little further north each year

Abstract

With annual damage estimated at up to $78 million, the exotic woodwasp, Sirex noctilio Fabricius (Hymenoptera: Siricidae), poses a very serious threat to commercial pine plantations throughout Australia. It has gradually increased its northward range since becoming established in mainland Australia around 1960. Previously restricted to temperate areas, where its host relationshipsare understood, and where effective management and control strategies were developed, it recently reached southern Queensland, close to valuable subtropical pine estates. While climate modelling predicts these regions as suitable for Sirex establishment, subtropical pines represent unstudied hosts, and biocontrol success may be compromised in these conditions; there is an urgent need to determine Sirex host and biocontrol relationships in the subtropics to prepare intervention strategies for its inevitable arrival. We have developed novel surrogate experimental techniques to enable assessments in the absence of the wasp, and we present the results of these trials here. We also discuss results from the ongoing nematode inoculation biological control program in place in Queensland, and woodwasp phenology in this newly invaded region.