Biology of the bark beetleIps grandicollis Eichhoff (Coleoptera:Scolytinae) and its arthropod, nematode and microbial associates: a review of management opportunities forAustralia

Abstract

AbstractThe five‐spined bark beetle,Ips grandicollis, is an exotic pest inAustralia that preferentially attacks stressed pine trees, includingPinus radiataD. Don, but it can also attack healthy trees. The beetle has been present inAustralia for 70 years, feeding principally on logging debris, with occasional outbreaks resulting in damage to plantations. Attack on trees stressed by drought, fire or storm damage leads to occasional significant losses. In recent years,I. grandicollishas been observed to attack ‘trap trees’ treated with herbicide to make them attractive toSirex noctilioFabricius as part of a successful biological control programme against this wood wasp.Ips grandicollisis able to tolerate a wide range of climatic conditions, and has an extensive geographical range (limited by host tree plantings). The economic impact ofI. grandicollisis exacerbated by adults vectoring a fungus,Ophiostoma ips(Rumbold) Nannfeldt, which discolours the outer sapwood and contributes to tree death. Nematodes also are also associated withI. grandicollis, both in the body cavity and under the elytra. The dominant nematode isContortylenchus grandicolliMassey, which is found internally, in haemocoel, the gut and the head region of the majority of adult beetles. Mites and bacteria are also associated withI. grandicollisbut their biology is not well known. Since the first detection ofI. grandicollisinAustralia, various bio‐control and other management strategies have been tested. While a better understanding of the microbial and nematode associates ofI. grandicollismay yield novel approaches for the management of this exotic pest, semiochemical‐based disruptants offer more immediate scope, particularly for protecting small areas of high value trees such as trap tree plots.