Flower colour- and sex-dependent local enhancement of flower visit behaviour in the swallowtail butterfly

Searches for food resources are time and energy consuming. Therefore, some animals have evolved strategies for the efficient location and selection of optimal resources. Typically, flower-visiting butterflies prefer brightly coloured, conspicuous flowers because they primarily locate flowers visually. However, such flowers are not always abundant across all seasons and times of day. Therefore, strategies to locate inconspicuous flowers are adaptive for butterflies. For example, the presence of other foragers on flowers can serve as a cue for the location and selection of appropriate flowers for nectar foraging. To investigate this phenomenon, we conducted laboratory experiments using Papilio xuthus to explore the effects of flower colour and the presence of other foragers on the flower visit behaviour of butterflies. Whether the visit rates of P. xuthus to inconspicuous flowers changed in the presence or absence of an insect dummy was also examined. Choice tests were conducted by presenting either two conspicuous or two inconspicuous flowers, one with and one without an insect dummy. Result showed that P. xuthus avoid conspicuous flowers with butterfly dummies. However, trials using inconspicuous flowers exhibited significantly higher visit rates and selectivity for flowers with an insect dummy, which indicates that this species uses the presence of other foragers as a cue to locate and select inconspicuous flowers. This tendency was more pronounced in males possibly because of sex differences in vision and foraging desire. Overall, the results indicate that P. xuthus shows context-dependent floral visit characteristics of local enhancement in foraging, dependent on flower colour and sex differences. To our knowledge, this study is the first to report on local enhancement in the flower visit behaviour of a butterfly. Such behaviour is an adaptation to a natural environment in which the availability of flower resources changes temporally. • Papilio xuthus uses other flower-visiting insects as a cue for local enhancement. • Local enhancement is associated with inconspicuous flowers and males. • Butterflies exhibit context-dependent behaviour to adapt to their environment. • This study is the first to report on local enhancement in butterfly flower visits.