Chemical examination of Swertia densifolia leaf essential oil and its repellent activity towards Apis cerana indica F.
Dattatraya G Naik, Chitra Dandge, Hemalata Puntambekar and Pradnya Deshpande
The alcoholic leaf extract of an Indian medicinal plant, Chirayata, Swertia densifolia (Griseb.) (Gentianaceae), is known to show dose-dependant attractant and repellent properties towards Apis cerana indica and Apis florea. We now report repellent activity of the essential oil obtained from these leaves on A. cerana indica F. Chemical examination of the essential oil was carried out by Gas Chromatography - Mass Spectrometry and hitherto unknown chemical constituents were identified as linalool, α–terpineol, stearic acid, hydroquinone and octadecanal. Structural assignments of the first four constituents were confirmed by comparison with the authentic samples. Bioassay of the formulations of linalool and α–terpineol in liquid paraffin showed that they were repellent to A. cerana. Beekeepers might be able to develop repellent formulations based on these findings.