Abstract

The first phase of the study involved evaluation of leaf and bud oils of clove,Syzygium aromaticum for their biocidal (i.e. ovicidal and larvicidal) activity againstAedes albopictus. Eggs and fourth instar larvae were exposed to different concentrations of the oils to investigate their comparative efficacy against the target mosquito species. In the second phase of the study, biocidal activity of ‘test formulation’ derived from the leaf oil and commercial mosquitocide, Prallethrin were estimated by the same method to compare the efficacy of the former with popular mosquitocides. Mortality data were analyzed by a computerized Log-Probit analysis (StatsDirect). Ovicidal assay of the oil samples recorded EC₅₀ values of 0.37 and 2.0 mg/ml respectively for leaf and bud oil. Larvicidal assay showed LC₅₀ and LC₉₅values of leaf oil as 5.3 and 7.03 mg/ml respectively, while bud oil recorded LC₅₀and LC₉₅ values of 17.84 and 23.99 mg/ml, respectively. The ‘test formulation’ recorded EC₅₀ value of 1.63 mg/ml, LC₅₀ of 3.67 mg/ml and LC₉₅ of 13.49 mg/ml respectively, indicating levels comparable to that of prallethrin. Third phase of the study involved chemical characterization of the oil samples using GC-MS. Eugenol constituted the major component of both the oils. The study demonstrated the potential of clove oil as a biocide against A. albopictus and warrants further standardization of the ‘test formulation’

Key words: Aedes albopictus, biocide, essential oil composition, eugenol,Syzygium aromaticum, test formulation.