Stone oak flowers are more likely generalist pollinated by insects rather than wind
摘要
The Fagaceae family includes lineages that exhibit entomophily (insect pollination) and anemophily (wind pollination). However, the insect pollinators of key entomophilous lineages, such as Lithocarpus (commonly known as stone oaks), remain poorly understood. This knowledge gap limits our understanding of their reproductive strategies and the ecological roles of mass flowering Lithocarpus in supporting biodiversity and broader ecosystem processes. In this study, we investigated insect visitation frequency to male and/or female flowers to identify the primary floral visitors and potential pollinators of two stone oak species, L. longipedicellatus and L. polystachyus, in the subtropical evergreen forest in Malipo County, China. We also assessed the relative attractiveness of pistillate (female) and staminate (male) flowers to insect visitors and compared visitation patterns between the two species. Our findings suggest that L. polystachyus and L. longipedicellatus are are potentially pollinated by a assemblage of insects, particularly Diptera and Coleoptera. Both species exhibit phenological and inflorescence traits consistent with insect pollination. In the absence of nectar, their andromonoecious inflorescences likely provided pollen as the primary reward for insect visitors. Notably, L. polystachyus received substantially more visits to its staminate flowers than L. longipedicellatus, a difference likely attributable to variation in inflorescence morphology, flower abundance, and habitat context. These results contribute valuable insight into the pollination biology of Lithocarpus and anemophilous pollination mechanisms in other insect-pollinated members of Fagaceae.