Electroantennogram (EAG) recordings

The solutions of 3 sex pheromone components (Z11-16:Ald, Z9-16:Ald, and Z9-14:Ald) were prepared in 50 ng/μL using hexane as solvent. EAG values were recorded by using our previous reported method^{60, 61}, and hexane solution was used as the control. Briefly, the antenna of unmated males (3 days after eclosion) was cut off at the base of the moth’s head with a knife blade, and a short fragment in terminal of the antenna was excised to keep better contact with the electrode. The antenna with both ends removed was connected by gel (SPECTRA 360, Fairfield, NJ, USA) to the two recording electrodes, respectively. The filter paper strip (2.5 × 0.9 cm) containing 10 μL test solution was allowed to evaporate solvent for 5 minutes, then the paper strip was inserted into a Pasteur pipette placed perpendicularly through a hole in a metal line tube with an airflow of 4 ml/s. Stimulations were achieved by directing a puff of air (4 ml/s) through the pipette with a timer-controlled solenoid valve. For each antenna to each sex pheromone compound, the EAG response was tested in three repeats with an interval of 30 seconds. The EAG signals were recorded as voltage waveforms with EAG-adapted software (Syntech^®, The Netherlands).