Abstract
Ips grandicollis is an exotic bark beetle pest of Pinus species in Australia. It is typically considered a secondary pest, however, under conditions that weaken host tree defences, I. grandicollis populations may rapidly increase to outbreak levels as the availability of host material increases. The implications of I. grandicollis infestations for the pine industry include logistical pressure to remove harvested logs before beetle attack, reduced value of logs due to sap-staining, tree mortality from mass attacks and biosecurity sanctions due to live interceptions of this pest offshore in exported logs. Despite the release of biocontrol agents as part of a national Ips management project in the 1980s, the impact of these agents on I. grandicollis populations remains unknown and management in Australia largely relies on silvicultural practices. Current methods do not adequately suppress I. grandicollis populations, particularly when extreme abiotic and biotic factors periodically increase tree susceptibility to attack. To enhance ongoing control efforts, (i) we present an overview of the Ips biocontrol project from 1981 to 1990, including the considerations into its design. Further, (ii) we highlight the roles of selected associates that have demonstrated biocontrol potential in North America and Europe and occur in Australia but have not been fully exploited as control options. Finally, (iii) we provide research and application directions regarding predatory beetles and entomopathogenic fungi, including the potential to improve parasitoid utilisation using host-associated semiochemicals to enhance the overall sustainable management of this pest in pine plantations.
