Autor(es): Lucia, Alejandro; Zerba, Eduardo; Masuh, Hector

Resumo: The relationships between physicochemical parameters of majority components of Eucalyptus essential oils and their insecticide effect were evaluated on Aedes aegypti (L.) (Diptera: Culicidae). The octanol-water partition coefficients of the monoterpenes were estimated by the atom/fragment contribution method and the vapor pressures were determined by our laboratory in previous studies. The larvicidal activity (LC50 ((ppm))) and knockdown effect (KT50 ((min))) of each component was determined. The results show that the toxicity of EOs main components of Eucalyptus on adults and larvae of A. aegypti is strongly related to their physicochemical properties (vapor pressure and Log P). However, the interaction of both variables (vapor pressure * Log P) explains the toxicological phenomenon more precisely. The regression models were expressed as follows: KT (50(min)) = -aEuro parts per thousand 10.9 + 3.7 * Log P + 1.9 * 1/P-vapor (R-2 = 0.80; F = 42.5) and LC (50(ppm)) = -aEuro parts per thousand 94.3 + 438.6 * 1/Log P + 2.8 * 1/P-vapor (F = 57.8; R-2 = 0.85). The six evaluated components present different functional groups. Therefore, it was considered to evaluate the monoterpenes as a group and separated in two groups: oxygenated monoterpenes (alpha-terpineol, 4-terpineol, and 1,8-cineole) and terpene hydrocarbons (gamma-terpinene, p-cymene, and alpha-pinene). The results show the regression models for each group as follows: (A) oxygenated terpenes: KT (50(min)) = -aEuro parts per thousand 515.3 + 1613.2 auaEuro parts per thousand 1/Log P + 5, 2 auaEuro parts per thousand 1/P-vapor (F = 3176.7 R-2 = 0.99) and LC (50(ppm)) = -aEuro parts per thousand 1679.4 + 5402.1 auaEuro parts per thousand 1/Log P + 12.7 auaEuro parts per thousand 1/P-vapor (F = 282.9; R-2 = 0.99). (B) Hydrocarbons terpenes: KT (50(min)) = 18.2 -aEuro parts per thousand 58.3 * 1/Log P + 2.7 * 1/P-vapor (F = 171.7; R-2 = 0.97) and LC (50(ppm)) = -aEuro parts per thousand 21.1 + 174.9 auaEuro parts per thousand 1/Log P -aEuro parts per thousand 14.3 auaEuro parts per thousand 1/P-vapor (F = 410.0; R-2 = 0.99). The association between the toxic effect of the evaluated monoterpenes against A. aegypti and the physicochemical properties can be better described when they are separated into functional groups (hydrocarbons vs. oxygenated terpenes).

Palavras-Chave: Essential Oils; Eucalyptus; Larvae; Coleoptera; Repellent; Fumigant; Vapors

Imprenta: Parasitology Research, v. 112, n. 12, p. 4267-4272, 2013

Identificador do objeto digital: 10.1007/s00436-013-3618-6

Descritores: Aedes aegypti - Larvicide ; Aedes aegypti - Repellent ; Aedes aegypti - Public health

Data de publicação: 2013

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