Abstract
Longicorn beetles (Coleoptera: Cerambycidae) and cossid moths (Lepidoptera: Cossidae) are insect borers that are major global pests of eucalypt plantations. In Australia, damage from borers and associated fungal invasion can reduce sawlog timber value by up to 90%. Despite this, there has been little research to date on determining the major predictors of the incidence or severity ofborer attack. The authors examined site- and landscape-scale drivers of borer damage from both insect families in two plantation species, Corymbia citriodora subsp. variegata (CCV) and Eucalyptus grandis, in Queensland and New South Wales, Australia. Twenty CCV and 19 E. grandis plantations were assessed for incidence, severity, and bole height of borer attacks, representing 4 200 CCV and 3 990 E. grandis trees in total. Landscape and site predictors were collected for each site through field surveys and from databases and analysed with the borer data to determine the relative importance of each variable in predicting the extent of borer attack. The authors demonstrate the extent to which the risk of borer attack can be mitigated by the grower through improved management protocols and discuss the relative importance of other extrinsic infl uences that are beyond industry control.