Deceit pollination and the effect of deforestation on reproduction in dioecious Schisandra sphenanthera (Schisandraceae) in central China

The fruits of Schisandra sphenanthera (dioecious) are used to produce Nan-Wuweizi, an important Chinese medicine. However, long-term exploitation and habitat destruction have threatened these plants in nature. Knowledge of the reproductive biology of S. sphenanthera is essential to help formulate a conservation strategy for these plants. Field studies were conducted at Jigong Mountain (JGM) and Jinji Valley (JJV) in Henan and Hubei Provinces, China. The reproductive biology of S. sphenanthera was analyzed at these sites, including population structure, pollination, floral morphology, and natural fruit set. The 11 populations at two sites were male biased. The primary floral visitors were gall midges (Resseliella sp., Cecidomyiidae; Diptera) and thrips (Thrips flavidulus; Thysanoptera). Floral visitor exclusion experiments and pollen load analysis indicate that gall midges are the primary pollinators. Pollen was the only floral reward for the gall midges. Female flowers attracted pollinators using deceit. The natural fruit set ratio in the cut forest site (JJV) was significantly lower than that at the JGM site, where habitats of S. sphenanthera were well preserved. This indicates that the life cycles of S. sphenanthera and the pollinating insects are vulnerable in disturbed (or cut) habitats.