Pollen meta-barcoding reveals different community structures of foraged plants by honeybees (Apis mellifera L.) along space-time gradient in Japan

The availability of pollen in urban-rural landscapes is an essential factor that influences the population dynamics of insect pollinators. The amount and diversity of pollen play a pivotal role in the foraging ecology of pollinators for their growth and health, but investigations on the spatio-temporal patterns of foraged plants remain rare, especially in cities as neo - ecosystems. Here, we explored the temporal foraging habits of a highly pollinator (Apis mellifera L.) in Tokyo, including different landscape classes from rural to urban areas. Mixed-pollen samples in each month and each location (N = 17) were analysed using DNA meta-barcoding to identify plants visited by honeybees. The results showed that the landscape class (rural, suburban and urban areas) explains spatial variations in pollen source-plant composition foraged by honeybees, but not in taxa richness. Furthermore, pollen diversity and pollen source-plant composition showed a strong seasonal dependence. A higher plant richness and foraged woody taxa was found to occur in spring, which was mainly dominated by the genera Prunus and Acer. In summer and autumn, the genera Trifolium and Plantago of the herbaceous stratum were the most visited plants. The Fabaceae, Rosaceae, Brassicaceae, Plantaginaceae, and Onagraceae plant families were the most frequently observed in all combined samples. The present study contributes to a deeper understanding of the foraging ecology of A. mellifera colonies across urban-rural gradient surrounding mega-cities such as Tokyo.

Automated summary

This study highlights the spatio-temporal patterns of foraging behavior of honeybees in urban-rural landscapes. Landscape type influences the composition of pollen source-plants, while taxa richness remains unaffected. The study also reveals a strong seasonal dependence of pollen diversity and source-plant composition.