Reduced hardness as an indicator of susceptibility of timbers to attack by Euophryum confine Broun

Abstract The influence of early-wood hardness on the tunnelling activity of Euophryum confine Broun (Coleoptera: Curculionidae) is reported. The hardness of Pinus nigra (Arnold) sapwood blocks was measured using a micro-hardness testing device that simulated a mandible. Hardness was influenced by moisture content and wood decay. Hardness was found to be significantly lower at 25% equilibrium moisture content than at 15% in both undecayed wood and in wood decayed to 10% average weight loss by the brown rot fungi Coniophora puteana (Schum. Fr.) Karst., Serpula lacrymans (Wulf. Fr.) Schroet. and white rot fungus Pleurotus ostreatus (Jacq. Fr.) Kumm. In addition to this loss of weight from the blocks, there was also a significant reduction in early-wood hardness. Adult tunnelling was assessed over 7 days by wood weight loss, after any fungal decay had been arrested. Greater weight losses were recorded in blocks that had undergone fungal decay or had increased moisture content. Assessments of early-wood hardness in wild infestations of E. confine showed weevils tunnelled, decayed wood within an early-wood hardness range between 8.1 and 44.3 N / mm 2 .