Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Generalist flower-visiting hoverflies as non-negligible actors in pollen transport network in a botanical garden: verification of a hoverfly pollen transport network using pollen DNA barcoding.

Abstract

Botanical gardens could serve as pollinator-friendly gardens and are suitable locations for investigating plant-pollinator interactions. Pollination in botanical gardens is a challenging topic of research, and its ecological function remains unclear in terms of pollination management for both pollinators and plants. Objective monitoring methods-including the selection of insect taxa and analytical methods-are required to elucidate plant-pollinator interactions in botanical gardens. In this study, we evaluated pollen transport networks using generalist hoverflies, as they are important pollinator insects, generalist flower visitors, and heterospecific pollen vectors that carry pollen over large distances. Hoverflies can form generalized pollen transport networks with an adequate abundance and wide distribution, and are easily collectable using sticky traps. Pollen grains on hoverfly bodies were identified based on pollen DNA barcoding using the ITS, rbcL, and trn regions. Bipartite pollen transport networks in the study period in 2018 and 2019 consisted of 116 plant taxa that were significantly generalized and showed similar structures in both years. The dominant plant taxa were two invasive species-Solidago canadensis and Bidens sp.-which had a significantly high eigenvector centrality in unipartite pollen transport networks. Hoverfly-mediated pollen transfer distances were 116-131 m on average and were significantly shorter in heterogeneous open environments. These findings suggest that hoverflies are non-negligible actors in pollen transport networks in the studied botanical garden.