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International audience; The essential oil from the leaves of Peperomia borbonensis from Reunion Island was obtained by hydrodistillation and characterized using GC-FID, GC/MS and NMR. The main components were myristicin (39.5%) and elemicin (26.6%). The essential oil (EO) of Peperomia borbonensis and its major compounds (myristicin and elemicin), pure or in a mixture, were evaluated for their insecticidal activity against Bactrocera cucurbitae (Diptera: Tephritidae) using a filter paper impregnatedbioassay. The concentrations necessary to kill 50% (LC50) and 90% (LC90) of the flies in three hours were determined. The LC50 value was 0.23 0.009 mg/cm2 and the LC90 value was 0.34 0.015 mg/cm2 for the EO. The median lethal time (LT50) was determined to compare the toxicity of EO and the major constituents. The EO was the most potent insecticide (LT50 = 98 2 min), followed by the mixture of myristicin and elemicin (1.4:1) (LT50 = 127 2 min) indicating that the efficiency of the EO is potentiated by minor compounds and emphasizing one of the major assets of EOs against pure molecules.

International audience; Analysis of the extracts contained in Burkea africana heartwood is studied with the aim of better understanding the reasons of the exceptional durability of this type of wood. The results obtained show that in spite of the fungicidal and termiticidal properties of certain products contained in the extracts, these properties do not allow to explain entirely the reasons of the durability. The strongly hydrophobic character of wood as its high dimensional stability would be also significant factors of its resistance. Analysis of the products present in the diethylether extracts indicates the presence of fats, waxes and squalene which could be the reason of the preceding results.; À propos de la durabilité du bois de cœur de Burkea africana. L'analyse des matières extractibles contenues dans le Burkea africana est étudiée dans le but de mieux comprendre les raisons de la durabilité exceptionnelle de ce type de bois. Les résultats obtenus montrent que malgré les propriétés fongicides et termiticides de certains produits contenus dans les extraits, ces dernières ne permettent pas d'expliquer entièrement à elles seules les raisons de la durabilité. Le caractère hydrophobe du bois ainsi que sa forte stabilité dimensionnelle seraient également des facteurs importants de sa résistance. L'analyse des produits présents dans les extraits éthérés indique la présence de graisses, de cires et de squalène pouvant être à la base des résultats précédents.