author(s)
N Rani, G Ponnudurai and TJ Harikrishnan

abstract
Essential oil was extracted from the fresh leaves of Lemon grass (Cymbopogon citratus) by hydro-distillation using Clevenger apparatus at 80° C for 3 - 4 hrs. One hundred gram of fresh leaves yielded maximum of 1.5 to 2 ml of oil and GC-MS analysis revealed 27 different components. In vitro efficacy of essential oil against larvae, pupae and adult flies at different concentrations viz., 50, 100, 150, and 200 µl was evaluated. The mortality of larvae, pupae and adult flies had increased with the concentration of the oil increasing. The LD₅₀ values of oil against larvae and pupae were 29.58, and 18.26 µl respectively. In the control group, 10.30 ± 0.31and 12.30 ± 0.22 per cent mortality of larvae and pupae respectively were observed. The fumigant toxicity against adult flies showed that the highest concentration of 200 µl caused 100 per cent mortality in 4.3 ± 0.11 minutes against no mortality of flies up to 2 days in the control group. The dead larvae from treated group appeared shrunken and black in colour, while histopathological study revealed bleb formation and Intestinal cell damage.