Plant–pollinator interactions along an urbanization gradient from cities and villages to farmland landscapes

Abstract

Urbanization affects pollinator diversity and plant–pollinator networks by changing resource availability locally and in the surrounding landscape. We experimentally established (N = 12) standardized plant communities in farmland, villages, and cities to identify the relative role of local and landscape effects on plant–pollinator communities along this urbanization gradient. We found that the number of flower visits by solitary bees, but not bumblebees, was highest in cities and lowest in farmland, with villages being intermediate, whereas syrphid flies exhibited lowest numbers in cities. Villages supported the richest pollinator communities, as they appeared to benefit from both farmland and city communities. Plant–pollinator network metrics such as robustness, interaction evenness, and interaction diversity decreased with increasing urbanization, although local plant richness increased toward urban areas. In conclusion, pollinator communities were most diverse and stable in farmland and village sites, despite the high plant richness in cities. The different composition of pollinator communities along the urbanization gradient suggests considering all three landscape types for conservation schemes.

Syrphidae of Southern Illinois: Diversity, floral associations, and preliminary assessment of their efficacy as pollinators

“…Bee families yielded from 19 (Colletidae) to 67 (Apidae) species, and butterflies including skippers (Lepidoptera: Rhopalocera) yielded 72 species. One reason for the high syrphid richness documented may be that Southern Illinois is predominantly rural; syrphid abundance and richness have both been shown to decline with increasing urbanization (Udy et al 2020). Seventeen species (25% of total) reported in this study have not been recorded in Illinois before (Table 1), according to records in Skevington et al (2019) and 10 datasets in GBIF.org (2020d).…”

Pathways for Novel Epidemiology: Plant–Pollinator–Pathogen Networks and Global Change

“…Overall, urbanisation favours generalist species [111] and very high levels of urbanisation reduce pollinator diversity [112] (Figure 1E). Urban environments thus generally produce a network containing fewer, generalised pollinator species, with high connectance and low evenness and robustness [113,114]. This network architecture may promote pathogen transmission and infections in concert with other pressures of urban settings.…”

Pollen analysis of cavity‐nesting bees (Hymenoptera: Anthophila) and their food webs in a city

“…These network interactions can be characterised by various metrics that indicate how the network is structured and how species interact to each other (Thébault & Fontaine, 2010). A study on bee‐plant communities performed in an urbanisation gradient in Germany has demonstrated that robustness, which is a qualitative metric that represents the network resistance to species extinctions (Burgos et al ., 2007), and interaction evenness presented lower values in cities when compared to farmland and villages (Udy et al ., 2020). Another important metric, network‐level specialisation (H 2 ′) (Blüthgen et al ., 2006), presented higher values in urban sites in comparison to agricultural lands, that is insect pollinators visited proportionally fewer plant species in urban areas (Theodorou et al ., 2017).…”