Floral and leaf-trap volatiles and their relationship to pollinator and prey attraction in Pinguicula moranensis (Lentibulariaceae)

Abstract

More than 140 years ago Darwin proposed that leaf-trap of carnivorous plants could produce odor to increase prey attraction; however, even now, there is limited information on the role of flower and leaf-trap volatile organic compounds (VOCs) in the attraction to pollinators and prey in carnivorous plants. Here, we recorded the floral visitors and prey of Pinguicula moranensis, a carnivorous plant with adhesive leaf-traps. In addition, the VOCs from flowers and leaf-traps were analyzed. Their role in the attraction of floral visitors and prey was experimentally tested using the skipper butterfly Thorybes dorantes and the fruit fly Drosophila melanogaster as models, respectively. In the field, flowers of P. moranensis were only visited by butterflies and most of the prey were dipterans. Six VOCs, predominantly benzenoids, were identified from floral scent samples. Twelve VOCs were identified from leaf-trap scent samples, mainly monoterpenoids and benzenoids. In experimental conditions, D. melanogaster significantly preferred the scent given off by the leaf-trap over the clean air, whereas the main floral visitor, T. dorantes significantly preferred the floral scent source over the clean air. However, D. melanogaster did not show preferences for the leaf-trap scent compared to the flower scent. These results showed that leaf-traps and flowers of P. moranensis emitted a specific composition and relative abundance of VOCs. In addition, we experimentally showed that floral VOCs attracted the main floral visitor species and leaf-traps attracted D. melanogaster, as a potential prey. The VOCs play a relevant role in attracting pollinators and prey in carnivorous plants.