Comparative analysis on visual and olfactory signals of Papilio xuthus (Lepidoptera: Papilionidae) during foraging and courtship

In this study, we examined the roles of visual and olfactory responses during foraging and courtship of the butterfly Papilio xuthus. Our results showed that P. xuthus was sensitive to color in the range of 350–500 nm. Visits of P. xuthus females and males to blue, purple, and red artificial cloth flowers were ♀ 54.90% and ♂ 39.22%, ♀ 19.61% and ♂ 35.29%, and ♀ 9.80% and ♂ 19.61%, respectively. Application of 10% honey on these artificial flowers resulted in an increase of 3.41 and 3.26 fold in flower visits by the butterfly in comparison with controls. When 10% honey water was sprayed on colorless artificial flowers, flower visits reduced seven fold for females and two fold for males, indicating that both visual and olfactory perceptions play important roles during foraging. During courtship, four types of chasing were observed in a natural population of P. Xuthus. The four types are males chasing females (49%), males chasing males (25%), females chasing males (13%), and females chasing females (10%). However, when odorless artificial mimics of butterflies were used, no significant differences were observed among these types of chasing, indicating that olfactory perception was crucial for the butterfly during courtship. Profiling volatile organic chemicals and individual bioassays revealed that α-farnesene might play an important role in distinguishing males from females during courtship of the butterfly.