Nematicidal Activity of the Essential Oils from Pilocarpus microphyllus (Rutaceae) Samples
The composition and nematicidal activity of the essential oils from the leaves of native and six cultivated varieties of P. microphyllus are reported. Twenty-nine compounds were identified (86.2% sesquiterpenes and 13.8% aliphatic ketones) of which (E)-caryophyllene, germacrene-D, caryophyllene oxide, 2-tridecanone, and 1-hydroxy-2-tridecanone were found in all of the analyzed oils. The nematicidal activity of all the oils was evaluated against the second-stage juvenile nematode Meloidogyne incognita. Essential oils from native P. microphyllus and varieties Xingu and Linha V showed high nematicidal activity, while no activity was found for the other oils. This result was associated with the high concentrations of both 2-tridecanone and 1-hydroxy-2-tridecanone in the active oils. Both ketones were isolated from one of the active oils and showed 100% activity at 1000 ppm concentration.