Huiles essentielles de trois espèces d’Eucalyptus d’Algérie

Abstract

The study was aimed to determine the chemical composition, toxicity effect and field varroacidal efficacy of essential oil from leaf of Eucalyptus robusta (Er), Eucalyptus sideroxylon (Es) and Eucalyptus globulus (Eg) grown in Algeria. The brine shrimp lethality (BSL) assay and bee hives infected by Varroa destructor were used to assess the toxicity and acaricidal effect, respectively. Steam distillation of (Er), (Es) and (Eg) leaves yielded 0.83%, 1.09 % and 0.93% (v/w) of essential oil (EO) respectively. GC/MS Analysis revealed 13 compounds for (Er), 36 for (Es) and 39 for (Eg). The main constituents for Er EO were 1,8- cineole (65,97%), p-cymene (7,83%) and o-cymene (4,75%), for Es EO 1,8-cineole (20,57%), octane (4.83%) and p-cymene (1,35%), and for Eg EO, 1,8-cineole (78.45 %), o-cymene (2.18 %), and isopinocarveole (1.74 %). The BSL assay of Er EO, Es EO and Eg EO revealed a highly toxic value of LC50 (µg/ml): 9.42, 34.80 and 67.55 respectively. Furthermore, field efficacy testing on bee hives infected with Varroa destructor has confirmed the effectiveness of Eucalyptus robusta essential oil (Er EO), (Es EO) and (Eg EO) and thymol (p < 0, 05) as varroacidal agents. Moreover (EEO + thymol) association was more effective than EEO or thymol alone. Finally the use of (EEO + thymol) may constitute a viable alternative to the thymol based commercial treatment.