What Are the Best Pollinator Candidates for Camelia oleifera: Do Not Forget Hoverflies and Flies

SIMPLE SUMMARY: Camellia oleifera is an important woody grain and oil plant worldwide. However, owing to a significant decline in the number of wild pollinators globally and the associated reduction in pollination services and seed production, camellia oil is in short supply. Therefore, it is important to evaluate the pollination mechanisms and efficiency of wild pollinators in C. oleifera seed production. We explored the pollination system of C. oleifera, focusing on the flower-visiting characteristics of its candidate pollinators. We found that Apis mellifera is the best candidate pollinator, but flies and hoverflies also play important roles in the pollination system. ABSTRACT: Camellia oleifera Abel. is an important woody oil plant, and its pollination success is essential for oil production. We conducted this study to select the best pollinator candidates for C. oleifera using principal component analysis and multi-attribute decision-making. Field observations of the flower-visiting characteristics of candidate pollinators were conducted at three sites. The insect species that visited flowers did not considerably differ between regions or time periods. However, the proportion of each species recorded did vary. We recorded eleven main candidates from two orders and six families at the three sites. The pollen amount carried by Apis mellifera was significantly higher than that of other insects. However, the visit frequency and body length of Apis mellifera were smaller than those of Vespa velutina. Statistical analysis showed that A. mellifera is the best candidate pollinator; Eristalis cerealis is a good candidate pollinator; Phytomia zonata, A. cerana, and V. velutina were ordinary candidate pollinators; and four fly species, Episyrphus balteatus, and Eristalinus arvorum were classified as inefficient candidate pollinators. Our study shows that flies and hoverflies play an important role in the pollination system. Given the global decline in bee populations, the role of flies should also be considered in C. oleifera seed production.