Reproductive ecology of Paphiopedilum spicerianum: Implications for conservation of a critically endangered orchid in China

Abstract

Orchid conservation requires a case by case, functional ecosystem approach. In this context, understanding orchid reproductive strategy would be beneficial to orchid conservation. In this study, we investigated the floral biology and pollination ecology of Paphiopedilum spicerianum, a critically endangered orchid in China. P. spicerianum is self-compatible, but dependent upon insects for pollination. Two hoverflies, Allobaccha nubilipennis and Episyrphus balteatus, were observed and confirmed as pollinators of P. spicerianum. E. balteatus was the main pollinator of P. spicerianum, having the higher visitation frequency during our observations over three years. P. spicerianum exploited E. balteatus by food deception, and shared the pollinator with co-flowering Polygonum pubescens (Polygonaceae), a nectar rewarding species. Although the population of P. spicerianum was very small and the habitat was highly fragmented, P. spicerianum achieved a stable reproductive success measured as natural fruit set (mean 25.7% pooled over three seasons). Co-flowering P. pubescens plants may play an important role in attracting pollinators and maintaining a stable reproductive success for P. spicerianum. These results demonstrate the interrelationships of plants, pollinators and food sources that need to be understood when developing conservation plans for endangered orchids.