The impacts of colorful oilseed rape on pollinator diversity and its pollination services

Flower color serves as a key trait for pollinators to locate pollen and nectar, potentially influencing pollinator diversity and pollination effectiveness, which may subsequently increase crop productivity. Based on large-scale cultivation and popularization of colorful flower oilseed rape, we assessed the impact of its flower color variation on pollinator communities and pollination functions. The experiments were conducted with a randomized block design (6 different flower-colored varieties of oilseed rape, each with 5 replications) over 2 consecutive years (2021-2022). Results showed  that colorful oilseed rape attracts a diverse array of pollinators and enhances pollination efficiency. Across the 2-year sampling period, we identified insect pollinators from 4 orders, 34 families, and 108 species, with Apis mellifera, Lasioglossum politum, and Delia platura emerging as dominant pollinators. No significant differences in pollinator attraction were observed across different flower colors of oilseed rape. Furthermore, the results revealed that insect pollination significantly enhanced the yield of colorful oilseed rape. However, this effect varied by year. In 2021, the fruit setting rate of the main branch and the fertilization rate of the main and lateral branches in open cages were significantly higher than those in closed cages, which excluded insect-pollinators. However, no significant yield differences were observed between flower colors in response to insect pollination in 2021. In conclusion, colorful oilseed rape can serve as a nectar resource and habitat for pollinators, aiding in the restoration of the diversity and abundance of wild pollinators, improving species turnover, and providing pollination services.