‘Pheromone-like’ properties of de-oiled leaf extract of Swertia densifolia towards Apis cerana indica F.
Dattatraya G Naik, Chitra Dandge and Pradnya Deshpande
Leaf extract of Swertia densifolia (Griseb.) (Gentianaceae) is known to show dose dependent attractant and repellent properties towards Apis cerana indica F. and A. florea. The essential oil of these leaves has recently been shown to possess repellent properties towards A. cerana indica. As the next logical step in this programme, we now report screening results of ethanolic extract of de-oiled leaves of S. densifolia on A. cerana indica. The extract showed dose dependent attractant properties at lower concentrations and repellent properties at higher concentrations, a behaviour similar to an attractant pheromone. TLC and HPLC analyses of the extract indicated the presence of six constituents. GC-MS analysis of the ethyl acetate soluble part of the extract showed the presence of diethyl fumarate as a major constituent, methyl linolenate and ethyl linoleate as constituents of intermediate concentration and ethyl palmitate as a minor constituent.