Data from: Generalisation and specialisation in hoverfly (Syrphidae) grassland pollen transport networks revealed by DNA metabarcoding

Pollination by insects is a key ecosystem service and important to wider
ecosystem function. Most species‐level pollination networks studied have a
generalised structure, with plants having several potential pollinators,
and pollinators in turn visiting a number of different plant species. This
is in apparent contrast to a plant's need for efficient conspecific
pollen transfer. The aim of this study was to investigate the structure of
pollen transport networks at three levels of biological hierarchy:
community, species and individual. We did this using hoverflies in the
genus Eristalis, a key group of non‐Hymenopteran pollinators. We
constructed pollen transport networks using DNA metabarcoding to identify
pollen. We captured hoverflies in conservation grasslands in west Wales,
UK, removed external pollen loads, sequenced the pollen DNA on the
Illumina MiSeq platform using the standard plant barcode rbcL, and matched
sequences using a pre‐existing plant DNA barcode reference library. We
found that Eristalis hoverflies transport pollen from 65 plant taxa, more
than previously appreciated. Networks were generalised at the site and
species level, suggesting some degree of functional redundancy, and were
more generalised in late summer compared to early summer. In contrast,
pollen transport at the individual level showed some degree of
specialisation. Hoverflies defined as “single‐plant visitors” varied from
40% of those captured in early summer to 24% in late summer. Individual
hoverflies became more generalised in late summer, possibly in response to
an increase in floral resources. Rubus fruticosus agg. and Succisa
pratensis were key plant species for hoverflies at our sites Our results
contribute to resolving the apparent paradox of how generalised pollinator
networks can provide efficient pollination to plant species. Generalised
hoverfly pollen transport networks may result from a varied range of
short‐term specialised feeding bouts by individual insects. The
generalisation and functional redundancy of Eristalis pollen transport
networks may increase the stability of the pollination service they
deliver.