The gland extracts and the synthetic chemicals were analysed on a Saturn 2200 GC/MS (Varian Walnut Creek, CA, USA) using an ionization voltage of 70 eV and a mass range of 30-650 m/z, equipped with two different capillary columns: a non-polar 30 m  0.25 mm ID  0.5 µm VF5-MS capillary column (Factor four, Varian Inc., USA) and a polar 30 m  0.25 mm ID  0.5 µm VF23-MS capillary column . In both the columns, the injection was splitless and the oven was programmed to increase from 80°C (held for 1 min) to 240 °C at 10 °C/min and then held for 13 min. Compounds were identified by comparing the retention time and mass spectra with those of synthetic compounds on two different capillary columns.