Mosquito Repellent and Larvicidal activity of a Gel Formulation from the Essential Oil of Eucalyptus globulus

Eucalyptus globulus L. belongs to the family Myrtaceae, a natural insecticide widely used as anti -microbial, anti-septic, analgesic, etc. The objective was to formulate gel formulation(Carbopol-940) from essential oil of Eucalyptus globulus and to evaluate its efficacy.

Eucalyptus oil was fractionated from the leaves of Eucalyptus globulus and characterized by GC-MS Instrumentation technique to detect the presence of active phytoconstituents. Then it is made into a gel formulation containing 12.5% v/v of active ingredient and then evaluated for stability study. The formulated gel was evaluated for its mosquito repellent potential using the laboratory method, arm in cage and the time of protection (% mosquito repellence) was calculated based on comparison with control arm. For determining the larvicidal activity, different concentrations of formulated E. globulus oil gel 0.1%, 0.2%, 0.3%, 0.4% v/v was prepared from the stock solution (5:25 Cineole: Acetone) and were tested against 4^th instar larvae of Aedes and Culex species. Mortality rate was recorded at 3, 6, 12, 24 and 48hrs as per the standard protocol.

Characterization data from GC-MS revealed the presence of active phytoconstituent 1,8 Cineole. The % of mosquito repellence at consecutive time points was found to be stable without much deviation. The larvicidal activity against species of larva- Culex and Aedes showed mortality rate at 0.3% v/v concentration with effective LC₅₀ values of 2625.418ppm for Aedes and 2448.979ppm for Culex species with 95% CI. (MicroProbit 3.0 software).

The formulated gel from Eucalyptus globulus was found to have potential application as mosquito repellent, larvicidal action and used as an alternative to synthetic products.