Interaction of milkweed butterflies with egret and jewel orchids: observations on pollinaria attachment to danaid butterflies on east Sulawesi (Indonesia) (Lepidoptera: Nymphalidae: Danainae; Orchidoideae: Habenarinae and Goodyerinae)

What is it about?

Species of the butterfly subfamily Danainae visit orchids, resulting in pollinaria being attached to their heads. In several habitats in east Sulawesi a remarkable percentage of Danainae specimens was observed with orchid pollinaria preferentially attached to their eyes. Among the 13 observed native Danainae species, seven carried pollinaria. Pollinaria attachment appears to be selective for Danainae as hundreds of specimens from other butterfly families were negative. Selectivity also concerns the orchid species, as attached pollinaria could be assigned to a Habenaria orchid and in one case only to an Anoectochilus. Efficient pollinaria attachment requires compatible morphological characters of butterfly and orchid. In this respect, the observed high pollinaria load of single butterflies is also important. Comparable investigations in southeast Sulawesi did not reveal danaid–orchid interactions. Further studies are required to prove orchid pollination by Danainae and to clarify the mechanism by which these butterflies are attracted to the orchids.

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