2.5. Female Adult Host Preference Experiment in Y-Tube Olfactometer

The olfactory choice response of female FAW moths to rice and corn was performed in a Y-tube olfactometer as described above with some modifications at 27 ± 2 °C. The experimental choice arena consisted of a glass Y-tube (7.5 cm for each arm and base, 15 cm total length, 10 mm i.d., 12.7 mm o.d.; Chemglass, Inc., Vineland, NJ, USA. Host preference of S. frugiperda female adult reared on either corn or rice plants were compared. All bioassays were conducted in a dark room. One day old female moths were used in the bioassays. In this case, 10 moths were introduced into the Teflon tube union between the Y-tube base and vacuum line as described above. The moth was given 40 min to make a choice between the plant odors emanating from each arm. Moths that remained motionless and were not able to make a choice within 40 min were recorded as neutral or non-responders and were excluded from the experiment. Separate experiments were performed for corn and rice population in every generation. A total of 30 female moths were used for each population in three replicates (each replicate consisted of 10 female moths).