2.5.2 Y-tube assays
Behavioral assays are performed with a glass Y-tube
olfactometer (10 cm body length; 8 cm arm length;
1.5 cm inner diameter; 60 degree for the angle of two arms). Air
aspirated with a vacuum pump (Qianxi Air Company, Beijing, China) was
filtered through an activated-charcoal filter and a sorbent cartridge
(Porapak Q, 50 mg, 80/100 mesh, Supelco, Bellefonte, PA, USA) with a 0.3
L/min flow rate. Experimental samples (fresh ripe fuji apples or crown
pears / 30 virgin female adults for 3 days after eclosion /
10-3 M ethyl butanoate and 10-3 M
ethyl hexanoate from crown pear volatiles) and control samples (DEPC
water/ 10-3 M HPLC purity grade hexane) were placed
into the two arm sides respectively. Each individual larva or male adult
was placed at the entrance of the olfactometer. The number of larvae or
male adults in each arm exceeded 2 cm and stayed for 30s were recorded
within 5 min. If larva or male adult made no choice within 5 min, it was
not counted. For each experiment, 30 male adults or
30~60 larvae were tested in the Y-tube
olfactometer. All assays were performed in the
behavior room at 25 ± 0.5℃ and 70% relative humidity. Behavioral assays
of male adults were operated under red light (0.61 lux). The
olfactometer was washed with detergent and water before each experiment.
Each experiment was repeated for three times.