Avaliação da resistência biológica das madeiras de Azadirachta indica A. Juss e Eucalyptus spp. produzidas e tratadas com CCA no Nordeste do Brasil

Abstract

This study aims to evaluate the treatability and biological resistance of Azadirachta indica A. Juss (neem) and Eucalyptus spp. woods produced in Northeastern Brazil and treated with type C chromated copper arsenate (CCA-C) using the Bethell method in an autoclave. The study included analyses of preservative penetration, distribution, and retention in the wood samples, as well as biological tests with drywood termites (Cryptotermes brevis) to assess the effectiveness of the treatment against xylophagous insect attack. The treatment process involved the application of an initial vacuum (560 mmHg for 30 minutes), pressure (10.0 kg/cm² for 60 minutes), and final vacuum (450 mmHg for 15 minutes), resulting in an average retention of 6.5 kg/m³ of the active ingredient. The samples were subjected to forced-feeding and feeding-preference tests to evaluate mass loss, damage, and insect mortality rate. CCA-C treatment was effective in protecting Eucalyptus spp. and Azadirachta indica woods against Cryptotermes brevis, significantly reducing mass loss and damage, and increasing termite mortality. The highest mass loss (1.17%) occurred in untreated Eucalyptus, while the lowest values were observed in the CCA-C treated samples, especially in Azadirachta indica (0.31%) and Eucalyptus (0.51%). Only the untreated Eucalyptus showed perforations (0.60), and the highest mortality rates were recorded in the treated woods. Azadirachta indica demonstrated good natural resistance, suggesting the presence of insecticidal compounds, and the use of CCA-C via the Bethell method proved effective in protecting against xylophagous attack.