RESUMO
Climate change, unseasonal fire and urbanization are contributing to the decline of Pinus caribaea var. bahamensis populations in the Turks and Caicos Islands (TCI). Infestation of pines with the invasive pine tortoise scale (PTS, Toumeyella parvicornis) is accelerating this decline. Pine trees in the Bahamas are larger and healthier and are not infested with PTS although they are subject to some of the same environmental pressures as the trees in TCI. Volatile compounds were collected from wild and nursery-reared P. caribaea var. bahamensis from TCI and the Bahamas and characterized using GC/MS analysis, to look for differences between the compounds detected in insect-infested pines of TCI and the healthy pines of the Bahamas. Ten compounds contributing at least 1% of the total detected peak areas in any one of the samples were selected for further study. Eight of these compounds were identified using authentic standards and mass spectral libraries. The main constituents in the samples were α- and ß-pinene as well as ß-phellandrene, and, together with ß-myrcene, their contents varied the most between samples collected at different locations. Principal-component analysis showed that the two structural isomers of pinene, together with ß-myrcene and ß-phellandrene, contributed 98.4% of the variance between samples. There was a positive relationship between the concentrations of the two structural isomers of pinene and between levels of ß-myrcene and ß-phellandrene. The results are discussed in relation to the biology and adaptations of invasive scale insects, the importance of monoterpenes in pine as a defense against insect predation, whether these compounds can be used as indicators of tree health, and future directions for research into conserving the Caicos pine.
Assuntos
Hemípteros , Herbivoria , Pinus/química , Pinus/fisiologia , Compostos Orgânicos Voláteis/química , Monoterpenos Acíclicos , Adaptação Fisiológica , Animais , Bahamas , Monoterpenos Bicíclicos , Compostos Bicíclicos com Pontes/análise , Monoterpenos Cicloexânicos , Cicloexenos/análise , Cromatografia Gasosa-Espectrometria de Massas , Hemípteros/fisiologia , Espécies Introduzidas , Monoterpenos/análise , Análise de Componente Principal , Compostos Orgânicos Voláteis/análise , Índias OcidentaisRESUMO
International trade in Brazilian rosewood, Dalbergia nigra (Vell.) Allemão ex Benth., is regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). One problem in enforcing these regulations is the difficulty in distinguishing the wood of D. nigra from that of a closely-related but unregulated species, Dalbergia spruceana Benth. Using LC-MS to analyse methanol extracts of xylaria specimens, we identified a chemical marker for D. nigra heartwood, and determined its structure as the neoflavonoid 6-hydroxy-7-methoxy-4-(4-methoxyphenyl)-2H-1-benzopyran-2-one (4'-O-methylmelanettin; dalnigrin), using spectroscopic techniques. Dalnigrin was present in all nine available heartwood specimens of D. nigra, but it was not detected in extracts of 59 other heartwood samples representing 15 species of Dalbergia, including D. spruceana. Five other phenolic compounds were also isolated from D. nigra heartwood and similarly identified as the neoflavonoids 3'-hydroxymelanettin, melanettin, melannein and dalbergin, and the isoflavone caviunin. In extracts of D. spruceana heartwood, pseudobaptigenin was identified by LC-MS to be a major phenolic component that was not detected in wood extracts of D. nigra. We conclude that chemical analysis, in combination with anatomical investigation, can provide persuasive evidence to support the positive identification of untreated heartwood of D. nigra.