Visual and Olfactory Responses of Seven Butterfly Species During Foraging

Abstract

Foraging responses of seven butterfly species were determined for flower models that differed in color, size, and depth of artificial corolla. We measured frequency of visits to flowers of various colors (red, orange, yellow, purple, and white) with or without the application of honey water to flower models. We found that the relative strength of butterfly response to visual versus olfactory cues differed among butterfly species. We suggest that the seven butterfly species tested exhibit four different patterns in how visual and olfactory cues were combined as determinants of foraging importance: (1) vision was given priority over olfaction (in Cethosia cyane and Danaus chrysippus); (2) olfaction was given priority over vision (Cethosia biblis, Idea leuconoe, and Tirumala limniace); (3) olfaction and vision were equally important (Catopsilia pomona); and (4) only olfaction was used (e.g., Danaus genutia, which was not sensitive to the five colors tested but very sensitive to the smell of honey in our experiments). In tests with flower models of different sizes, the visitation frequency of C. cyane, I. leuconoe, and D. chrysippus increased with increasing corolla diameter, provided flowers were sprayed with honey water. C. cyane and D. chrysippus showed this trend because of their strong dependence on visual cues. In contrast, I. leuconoe with its large body size preferred larger flowers, it could be that butterflies need more nectar to support its large body size. Catopsilia pomona tended to visit large and middle-sized flowers because it used both vision and odor to detect food, large or middle-sized flowers could have more vision and odor stimulation than small flowers for foraging butterfly. The other three butterfly species did not show that trend because of lack of dependence on visual cues. There was no correlation between visitation frequency and corolla depth within particular butterfly species. In conclusion, the foraging strategies of butterflies are not only mainly determined by the weights given to visual and olfactory cues, but also affected by body size.