Comparison of prey fauna in tropical red traps versus temperate whitish traps in carnivorous Drosera indica complex (Droseraceae)

Certain carnivorous plant species display geographical variation in trap coloration, which may impact interactions with prey. Our study focused on Drosera indica (Droseraceae) in tropical Thailand and its phylogenetically related species Drosera toyoakensis in temperate Japan. Drosera indica in Thailand has green leaf blades with red tentacles when flowering, making the entire trap appear red. In contrast, D. toyoakensis in Japan has green leaf blades with green-white tentacles when flowering, and the entire trap appears white. Field observations revealed statistically significant differences in taxa and size of prey caught by D. indica and D. toyoakensis. Both species caught small flies, but D. toyoakensis additionally caught larger flies and butterflies, including pollinators. These differences in prey composition may reflect differences in trap coloration that evolved under different selection pressures for capturing prey. However, trap coloration and prey assemblages were influenced by various factors, and further research is required to elucidate their evolutionary significance.