Insecticidal activity of the essential oil from fruits and seeds of <it>Schinus terebinthifolia </it>Raddi against African malaria vectors

• Main Authors: Mosha Franklin, Nyindo Mramba, Kweka Eliningaya J, Silva Ary G
• Format: Article
• Language: English
• Published: BMC 2011-07-01
• Series: Parasites & Vectors
• Online Access: http://www.parasitesandvectors.com/content/4/1/129

<p>Abstract</p> <p>Background</p> <p>Alternative insecticides for the control of malaria and filarial vectors are of paramount need as resistance is increasing among classes of insecticides currently in use in the public health sector. In this study, mosquitocidal activity of <it>Schinus terebinthifolia </it>essential oil against <it>Anopheles gambiae </it>s.s., <it>An. arabiensis </it>and <it>Culex quinquefasciatus </it>was assessed in laboratory, semi- field and full- field conditions</p> <p>Method</p> <p>Twenty third instar larvae of both <it>Anopheles gambiae </it>s.s. and <it>Cx. quinquefasciatus </it>were exposed to different dosages of plant extract in both laboratory and semi- field environments. Observation of the mortality response was assessed at intervals of 12, 24, 48 and 72 hours. Adult semi- gravid female mosquitoes were exposed to papers treated with <it>S. terebinthifolia </it>and compared with WHO standard paper treated with alphacypermethrin (0.05%).</p> <p>Results</p> <p>Gas chromatography, coupled to mass spectrometry, identified 15 compounds from <it>S. terebinthifolia </it>extracts, the most abundant identified compound was δ-3-carene (55.36%) and the least was γ-elemene (0.41%). The density of the oil was found to be 0.8086 g/ml. The effective dosages in the insectary ranged from 202.15 to 2625.20 ppm and were further evaluated in the semi- field situation. In the laboratory, the mortality of <it>Cx. quinquefasciatus </it>ranged from 0.5 to 96.75% while for <it>An. gambiae </it>s.s it was from 13.75 to 97.91%. In the semi- field experiments, the mortality rates observed varied for both species with time and concentrations. The LC₅₀and LC₉₅value in the laboratory was similar for both species while in the semi- field they were different for each. In wild, adult mosquitoes, the KT₅₀for <it>S. terebinthifolia </it>was 11.29 minutes while for alphacypermethrin was 19.34 minutes. The 24 hour mortality was found to be 100.0% for <it>S. terebinthifolia </it>and 75.0% for alphacypermethrin which was statistically significant (<it>P </it>< 0.001).</p> <p>Conclusion</p> <p>The efficacy shown by essential oils of fruits and seeds of <it>S. terebinthifolia </it>has given an opportunity for further investigation of individual components of these plant extracts and to evaluate them in small- scale field trials.</p>