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Hoverfly Communities in Semi-Natural Grasslands, and their Role in Pollination / Andrew M. Lucas
Swansea University Author: Andrew M. Lucas
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DOI (Published version): 10.23889/SUthesis.40892
Pollination is an ecosystem service critical to both crop production and the functioning of many ecosystems. Hoverflies (Syrphidae) are a key group of non-hymenopteran pollinators. Using a combination of field and molecular techniques, this thesis explored hoverfly communities in grasslands, investi...
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Pollination is an ecosystem service critical to both crop production and the functioning of many ecosystems. Hoverflies (Syrphidae) are a key group of non-hymenopteran pollinators. Using a combination of field and molecular techniques, this thesis explored hoverfly communities in grasslands, investigating how they are structured, and their possible role in pollination. In addition, it also created a library of hoverfly DNA barcodes that has applications for monitoring. Hoverfly abundance and species richness was not related to grassland plant community, but was influenced by flower abundance. Distinctive hoverfly communities were also associated with agriculturally unimproved grassland communities. Focussing on species-rich marshy grasslands, a four year study showed that hoverfly abundance and species richness was influenced by weather conditions. Hoverfly abundance was at a maximum at a daily mean temperature of 15°C and at moderate rainfall, declining with both high and low temperature and rainfall. Species-richness declined with increasing daily temperature. Sequences of the standard animal barcode COI were obtained from 82 hoverfly species caught in Britain. This was added to world-wide publicly available sequences for British species to create a library of over 70% of the British hoverfly fauna. These barcodes were effective at distinguishing hoverfly species, although discrimination was poor in a small number of genera. By DNA metabarcoding pollen derived from hoverflies, the structure of hoverfly pollen transport networks in marshy grasslands was investigated. In Eristalis species, networks were generalised at the whole network and species level, but showed some specialisation by individual hoverflies. Networks of 11 hoverfly species showed that although pollen carried by hoverflies came from a few common plant taxa, different hoverfly species carried distinctive pollen loads derived from at least 40% of the entomophilous plants present. Collectively, these results increase our understanding of hoverfly community function, and their role in grassland ecosystems.
A selection of third party content is redacted or is partially redacted from this thesis.
Faculty of Science and Engineering