A filmed copulation of Ctenoplectra (Ctenoplectrini, Apidae) bees suggests that males may chemically mark females

Recent fieldwork on tropical bees has revealed that males of Ctenoplectrini, Tapinotaspidini, and Tetrapediini collect floral oils, but it remains unknown for which purpose. Observations and chemical tests in Yunnan show that at least 31 species of Dendrobium and two of Galeola orchids have oil hairs on their petals attracting male Ctenoplectra cornuta who collect the secretion in the same way as do females, which however prefer cucurbit flowers. We observed territoriality and mating on flowers and present a filmed copulation sequence during which the male grasps the female’s scutellum with his mandibles and repeatedly brushes her metasomal fringes with his hind legs and her hind scopae with his mid legs. We hypothesize that male Ctenoplectra scent-mark females during mating, which would explain why the males collect floral oils. Mating behavior has so far been documented in but a few dozen solitary bees, and it is for this reason that we here make available the first filmed copulation of any Ctenoplectrini.