Noctuid moths as pollinators of Habenaria sagittifera (Orchidaceae): floral adaptations for the transfer of pollinaria on the thoraxes of moths.

Abstract

Orchids attach their pollinaria (cohesive masses of pollen) to specific body parts of flower visitors, but usually not to the hairy and scaly body parts of flower-visiting moths, because hairs and scales are easily detached. We demonstrate that pollinaria of Habenaria sagittifera (Orchidaceae) are transferred among flowers on the hairy thoraxes of moths in Japan. Diurnal and nocturnal insects visited the orchid flowers. However, pollinaria were attached only to the hairy thoraxes of plusiine moths (Lepidoptera: Noctuidae). All pollinaria were directly attached to the ventral thorax surfaces at the bases of hairs. Orchid spur lengths matched plusiine proboscis lengths so that nectar-feeding moths contacted the viscidia (sticky pads of pollinaria) and stigma. Other flower visitors did not contact the viscidia or stigmas while feeding on nectar. Habenaria sagittifera appears to have a floral morphology that is adaptive for the transfer of pollinaria on the thoraxes of plusiine moths.