Lyctine susceptibility of selected hardwoods

Abstract

Summary The lyctine susceptibility of 16 timber species, hybrids and geographical types was examined in this study. Several of the timbers had been placed previously in a ‘rarely susceptible’ category, but such uncertain ratings are not acceptable for standards and compliance purposes. Timber specimens were exposed to three species of lyctine beetles in an insectary. New criteria were developed to divide the problematic ‘rarely susceptible’ species, including designating a species as non-susceptible if significant damage was limited to 6 mm depth, as this outer region is routinely lost upon sawing or peeling. Lyctine-susceptible species were Erythrophleum chlorostachys, Eucalyptus delegatensis grown in Tasmania but not Victoria or NSW, Eu. regnans x Eu. obliqua hybrid, Cotymbia nesophila, Eu. fibrosa, Eu. grandis, Eu. crebra, Eu. argophloia, Eu. dunnii, Eu. regnans from Tasmania and Eu. saligna. Eu. grandis x Eu. saligna hybrid is probably lyctine-susceptible as both parent species were susceptible. The non-lyctine-susceptible species were Eu. cloeziana, Eu. pilularis, Eu. sieberi and Eu. tetradonta.