Essential oil composition and larvicidal activity of Toddalia asiatica roots against the mosquito Aedes albopictus (Diptera: Culicidae).

The aim of this research was to determine larvicidal activity of the essential oil derived from roots of Toddalia asiatica (L.) Lam. and the isolated constituents against the larvae of the Culicidae mosquito Aedes albopictus. Essential oil of T. asiatica roots was obtained by hydrodistillation and analyzed by GC and GC-MS. A total of 58 components of the essential oil of T. asiatica roots were identified. The essential oil has almost same content of (35.41 %) of sesquiterpenoids and monoterpenoids (31.87 %). The principal compounds in T. asiatica essential oil were geraniol (9.84 %), D-limonene (7.52 %), isopimpinellin (6.62 %), α-gurjunene (6.25 %), and 4-vinylguaiacol (5.94 %). Based on bioactivity-directed fractionation, geraniol, D-limonene, and isopimpinellin were isolated from T. asiatica root essential oil. Geraniol, D-limonene, and isopimpinellin exhibited strong larvicidal activity against A. albopictus with LC(50) values of 30.13, 19.84, and 32.05 μg/ml, respectively, while the essential oil of T. asiatica had an LC(50) value of 69.09 μg/ml. The result indicated that the essential oil of T. asiatica roots and the three isolated constituents have potential for use in control of A. albopictus larvae and could be useful in search of newer, safer, and more effective natural compounds as larvicides.