Windborne migration amplifies insect-mediated pollination services

Abstract

Worldwide, hoverflies (Syrphidae: Diptera) provide crucial ecosystem services (ES) such as pollination and biological pest control. Although many hoverfly species exhibit migratory behavior, the spatiotemporal facets of these movement dynamics and their ES implications are poorly understood. In this study, we use long-term (16 yr) trapping records, trajectory analysis and intrinsic (i.e., isotope, genetic, pollen) markers to describe migration patterns of the hoverfly Episyrphus balteatus in China. Our work reveals long-range, windborne migration with spring migrants originating in northern China and exhibiting return migration during autumn. Given the substantial night-time dispersal of E. balteatus, this species possibly adopts a dual migration strategy. The extensive genetic mixing and high genetic diversity of E. balteatus populations underscore its adaptive capacity to environmental disturbances e.g., climate change. Pollen markers and molecular gut-analysis further illuminate how E. balteatus visits min. 1,012 flowering plant species (39 orders) over space and time. By thus delineating E. balteatus trans-regional movements and pollination networks, we advance our understanding of its migration ecology and facilitate the design of targeted strategies to conserve and enhance its ecosystem services.