Chemical Composition and Bioefficacy of Essential Oil from Bay Laurel Shrub (Laurales: Lauraceae) against Culiseta longiareolata (Macquart) (Diptera: Culicidae) Larvae

An essential oil extracted from bay laurel, Laurus nobilis (L.), was chemically characterized and tested against fourth-instar Culiseta longiareolata (Macquart) (Diptera: Culicidae). Percentage composition of the oil in L. nobilis was 0.96, and gas chromatography-mass spectrometry analysis identified 56 components with eucalyptol (25.62%), linalool (11.83%), methyl eugenol (10.07%), and camphene (10.18%) as the major constituents. Laboratory bioassays demonstrated significant larvicidal activity of the oil extract with cumulative median lethal concentrations (i.e., LC50) of 203.7 parts per million (ppm) at Day 1, 171.9 ppm at Day 3, and 85.1 ppm at Day 7 after exposure. The essential oil also affected egg hatch and sex ratio of the progeny. These results suggest that the essential oil extracted from L. nobilis has potential for development as a management tactic directed against Cs. longiareolata.