Observations of putative pollinators of Hemipilia flabellata Bur. et Franch.(Orchidaceae) in north-west Yunnan Province, China

Abstract

Interactions between Hemipilia flabellata and anthophilous insects were studied in northwestern Yunnan, China during June–July of 1996 and 1997. Twenty-seven species of insects were seen visiting the flowers of this species, although only male and female individuals of the bee Anthophora mangkamensis Wu were observed carrying the pollinaria. The frequency of visits by A.mangkamensis to this orchid was rather low. Pollinating bees normally sampled only the lowermost flowers in an inflorescence, staying for 1–3 seconds. This species is also characterized by low pollination, low fruit set (1–22%) and a very striking decrease in fruit production from bottom to top of the inflorescence. All of these indicate that the orchid may rely on deception to attract visitors. Ajuga forrestii Diels (Labiatae) appears to be the main or exclusive subsidiary nectar source for A.mangkamensis during the flowering period of H.flabellata. It appears that H.flabellata utilizes a food deceit pollination strategy for pollination. The orchid benefits from the great variation or flowers in colour and shape. Phenological, functional-morphometric and distribution data indicate that A.mangkamensis is an optimal pollinator of H.flabellala and thus the anthecological adaptation of the orchid to the pollen vector may be unique.