Chemical composition and larvicidal activities of the essential oil of Zanthoxylum armatum DC (Rutaceae) against three mosquito vectors

Background & objectives: In view of the recently increased interest in developing plant origininsecticides as an alternative to chemical insecticide, this study was undertaken to assess the larvicidalpotential of the essential oil from the seeds of Zanthoxylum armatum DC [syn. Z. alatum Roxb](Rutaceae) against three medically important species of mosquito vectors, Aedes aegypti, Anophelesstephensi and Culex quinquefasciatus.Methods: Essential oil was hydro distilled in the laboratory from the seeds obtained from the marketand the chemical constituents of the oil were determined using GC/GC-MS. Bioefficacy of theessential oil was evaluated under laboratory conditions using III instar mosquito larvae.Results: Among the three mosquito species tested, Cx. quinquefasciatus was the most sensitive(LC50 = 49 ppm) followed by Ae. aegypti (LC50 = 54 ppm) and An. stephensi (LC50 = 58 ppm). GCMSanalysis of the oil revealed at least 28 compounds, consisting mainly of oxygenated monoterpenes(75%) and monoterpenes (22%). Linalool though constituted a major part (57%), failed to produceany appreciable mortality when tested alone.Interpretation & conclusion: From the results it can be concluded that the larvae of the three mosquitospecies were susceptible to the essential oil composition. Such findings would be useful in promotingresearch aiming at the development of new agent for mosquito control based on bioactive chemicalcompounds from indigenous plant sources as an alternative to chemical larvicides

Chemical Composition and Larvicidal Activities of the Himalayan Cedar, Cedrus deodara Essential Oil and Its Fractions Against the Diamondback Moth, Plutella xylostella

Plants and plant-derived materials play an extremely important role in pest management programs. Essential oil from wood chips of Himalayan Cedar, Cedrus deodara (Roxburgh) Don (Pinales: Pinaceae), was obtained by hydrodistillation and fractionated to pentane and acetonitrile from which himachalenes and atlantones enriched fractions were isolated. A total of forty compounds were identified from these fractions using GC and GC-MS analyses. Essential oils and fractions were evaluated for insecticidal activities against second instars of the diamondback moth, Plutella xylostella L. (Lepidoptera: Yponomeutidae), using a leaf dip method. All samples showed promising larvicidal activity against larvae of P. xylostella. The pentane fraction was the most toxic with a LC50 value of 287 µg/ml. The himachalenes enriched fraction was more toxic (LC50 = 362 µg/ml) than the atlantones enriched fraction (LC50 = 365 µg/ml). LC50 of crude oil was 425 µg/ml and acetonitrile fraction was LC50 = 815 µg/ml. The major constituents, himachalenes and atlantones, likely accounted for the insecticidal action. Present bioassay results revealed the potential for essential oil and different constituents of C. deodara as botanical larvicides for their use in pest management

Evaluation of anti-mosquito properties of essential oils

129-133Essential oils from Cedrus deodara, Eucalyptus citriodora, Cymbopogon flexuous, C. winterianus, Pinus roxburghii, Syzygium aromaticum and Tagetes minuta were evaluated for bioactivity against the adults of Culex quinquefasciatus and Aedes aegypti. Serial dilutions of the oils were made in deodorized kerosene to obtain a range of concentrations (0.5-10%) and the adults were exposed to the vapour of the different oils for 1h in WHO kits for sensitivity testing. C. winterianus and S. aromaticum oils were equi effective and found most effective with LC50 and LC95 values respectively at 0.5 and 0.9 % for C. quinquefasciatus and 1.0 and 2.0 % for A. aegypti. Activity was found in the order: S. aromaticum > C. flexuous > E. citriodora > C. winterianus > C. deodara > T. minuta