EFFECT OF EXTRACTIVE CONTENTS ON NATURAL RESISTANCE OF FIVE DIFFERENT WOODS TO XILOPHAGAUS TERMITES ATTACK

Quando o homem deixou de ser n\uf4made, teve de se adaptar \ue0s novas condi\ue7\uf5es, passando a empregar a madeira para energia, instrumentos de ca\ue7a e defesa e elementos construtivos diversos. Desde ent\ue3o, em fun\ue7\ue3o dos usos e do r\ue1pido crescimento, a import\ue2ncia da madeira vem se acentuando, principalmente porque sua explora\ue7\ue3o agride menos o ambiente quando comparada a outros materiais n\ue3o renov\ue1veis. Embora existam v\ue1rias pesquisas sobre Eucalyptus e Pinus , estudos com outras esp\ue9cies s\ue3o incipientes, principalmente quanto ao efeito dos extrativos na resist\ueancia natural das madeiras. Assim, o objetivo da pesquisa foi avaliar a influ\ueancia do teor de extrativos na resist\ueancia natural das madeiras de Acacia mangium , Casuarina sp., Eucalyptus cloeziana , Corymbia torelliana e Tectona grandis ao t\ue9rmita xil\uf3fago Nasutitermes corniger , esp\ue9cie de ocorr\ueancia frequente em v\ue1rias regi\uf5es no Brasil. De cada esp\ue9cie foram retirados corpos de prova, com dimens\uf5es de 2,00 x 10,16 x 0,64 cm (radial x longitudinal x tangencial) em quatro posi\ue7\uf5es no sentido medula-alburno (cerne interno, cerne intermedi\ue1rio, cerne externo e alburno). As madeiras foram expostas \ue0 a\ue7\ue3o dos cupins durante 45 dias em ensaio de prefer\ueancia alimentar. Amostras n\ue3o selecionadas para o ensaio com cupins foram transformadas em serragem e o teor de extrativos obtido ao empregar a fra\ue7\ue3o que passou pela peneira de 40 e ficou retida na de 60 mesh. A resist\ueancia natural n\ue3o esteve associada ao teor de extrativos presentes na madeira. A resist\ueancia das madeiras variou no sentido medula-alburno, com padr\ue3o vari\ue1vel para cada esp\ue9cie. As madeiras mais resistentes foram Tectona grandis e Corymbia torelliana e a mais deteriorada a Acacia mangium.When man stopped being nomadic, he had to adapt to new conditions, and started employing wood for energy, hunting and defense instruments and miscellaneous constructive elements. Since then, in the light of usages and rapid growth, the importance of wood has been increasing, primarily by their exploitation assaults less the environment when compared to other non-renewable materials. Although there are several researches about Eucalyptus and Pinus, but studies with other species are incipient mainly about the extractive effects on the wood natural resistance. Thus, this research aimed to assess the influence of extractive contents with the natural resistance of Acacia mangium, Casuarina sp. Eucalyptus cloeziana, Corymbia torelliana and Tectona grandis woods to Nasutitermes corniger xylophagous termite, species of frequent occurrence in several regions in Brazil. From each species, test samples were taken, with dimensions of 2.00 x 10.16 x 0.64 (radial x longitudinal x tangential) in four positions in the medulla-sapwood direction (internal core, intermediate core, outer core and sapwood). The woods were exposed to the action of termites for 45 days in a food preference assay. The samples not selected for the test with termites were turned into sawdust and the extractive contents were obtained by using the fraction which passed through the sieve 40 and was retained in 60 mesh. The natural resistance has not been linked to extractive levels present in the wood. The resistance of wood varied in medulla-sapwood direction, with default variable for each species. The more resistant timbers were Tectona grandis and Corymbia torelliana and the most deteriorated was Acacia mangium