title: Insecticidal activities of leaf and twig essential oils from Clausena excavata against Aedes aegypti and Aedes albopictus larvae.
abstract: BACKGROUND
  The current study investigates, for the first time, the mosquito larvicidal activities of leaf and twig essential oils from Clausena excavata Burm. f. and their individual constituents against Aedes aegypti L. and Aedes albopictus Skuse larvae. The yields of essential oils obtained from hydrodistillation were compared, and their constituents were determined by GC-MS analyses.
  
  
  RESULTS
  The LC(50) values of leaf and twig essential oils against fourth-instar larvae of Ae. aegypti and Ae. albopictus were 37.1-40.1 microg mL(-1) and 41.1-41.2 microg mL(-1) respectively. This study demonstrated that C. excavata leaf and twig essential oils possess mosquito larvicidal activity, inhibiting the growth of mosquito larvae for both species at a low concentration. In addition, results of larvicidal assays showed that the effective constituents in leaf and twig essential oils were limonene, gamma-terpinene, terpinolene, beta-myrcene, 3-carene and p-cymene. The LC(50) values of these constituents against both mosquito larvae were below 50 microg mL(-1). Among these effective constituents, limonene had the best mosquito larvicidal activity, with LC(50) of 19.4 microg mL(-1) and 15.0 microg mL(-1) against Ae. aegypti and Ae. albopictus larvae respectively.
  
  
  CONCLUSIONS
  The findings suggested that the essential oils from Clausena excavata leaf and twig and their effective constituents may be explored as a potential natural larvicide.
authors.affiliation: Experimental Forest, National Taiwan University, Nan-Tou 55750, Taiwan.
authors.forename: Sen-Sung
authors.initials: SS
authors.lastname: Cheng
authors.forename: Hui-Ting
authors.initials: HT
authors.lastname: Chang
authors.forename: Chun-Ya
authors.initials: CY
authors.lastname: Lin
authors.forename: Pin-Sheng
authors.initials: PS
authors.lastname: Chen
authors.forename: Chin-Gi
authors.initials: CG
authors.lastname: Huang
authors.forename: Wei-June
authors.initials: WJ
authors.lastname: Chen
authors.forename: Shang-Tzen
authors.initials: ST
authors.lastname: Chang
mesh_terms: D000330:Aedes / Q000187:drug effects*; D000818:Animals; D054700:Clausena / Q000737:chemistry*; D053138:Cyclohexenes / Q000737:chemistry / Q000494:pharmacology; D007306:Insecticides / Q000737:chemistry / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D000077222:Limonene; D009822:Oils, Volatile / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry*; D010938:Plant Oils / Q000737:chemistry / Q000494:pharmacology; D018520:Plant Shoots / Q000737:chemistry*; D013729:Terpenes / Q000737:chemistry / Q000494:pharmacology
chemical_list: D053138:Cyclohexenes; D007306:Insecticides; D009822:Oils, Volatile; D010938:Plant Oils; D013729:Terpenes; D000077222:Limonene