Urbanization alters the abundance and composition of predator communities and leads to aphid outbreaks on urban trees

Abstract

Urbanization can affect arthropod abundance in different ways. While species with narrow habitat range and low dispersal ability often respond negatively to urban environments, many habitat generalist species with good dispersal ability reach high densities in city centers. This filtering effect of urban habitats can strongly influence predator-prey-mutualist interactions and may therefore affect the abundance of predatory and phytophagous species both directly and indirectly. Here, we assessed the effect of urbanization on aphids, predatory arthropods, and ants on field maple (Acer campestre) trees in and around the city of Budapest, Hungary. We used the percentage of impervious surfaces within a 500 m radius of each site as an index of the degree of urbanization. We found that the abundance of aphids increased with increasing level of urbanization. However, abundance of predatory arthropods and occurrence of poorly dispersing species within the predator community were negatively related to urbanization, and we identified these two independent factors as significant predictors of aphid abundances. The abundance of ants decreased with urbanization, and contrary to our expectations, did not affect the abundance pattern of aphids. Our results suggest that urbanization, by altering the abundance and composition of predator communities, can disrupt biological control of aphid populations, and thus may contribute to the aphid outbreaks on urban trees.

Downtown Diet: a global meta-analysis of urbanization on consumption patterns of vertebrate predators

“…We expect the effect sizes to positively correlate with the HFI, indicating that as the intensity of anthropogenic pressure increased, the magnitude of change to predation would increase. Predator diversity and density, and thus predation rates and prey selection, are correlated with the components used to calculate the HFI, such as human population density and land-use conversion, underpinning our expectation that the degree of urbanization would explain variation in predator diet effect sizes (Eötvös et al, 2018;Korányi et al, 2020).…”

Level of urbanization and habitat type, and not patch size, influence predacious arthropod diversity patterns of urban grasslands in South Africa

“…Since ruderal grassland, independent of urban settlement, had a higher disturbance intensity, Sattler et al (2011) suggested that such grasslands might have fewer, but more resilient arthropod species. Rangelands exhibited higher diversity than the ruderal and fragmented grasslands, probably due to less disturbance and fragmentation as well as the larger availability of structural habitat variation provided in more natural areas (Mata et al 2017, Botha et al 2018Koranyi et al 2021).…”

“…Adams et al (2020) reported that urban arthropods are affected by a mixture of fine, local, and landscape-scale mechanisms. Thus vegetation diversity, cover, structure, frequency of mowing at a fine scale (Lowe et al 2017(Lowe et al , 2018Philpott et al 2020;Koranyi et al 2021), the mosaic of the urban green spaces within a city, level of urbanization and isolation at a local scale (Delgado de la Flor et al 2020;Fenoglio et al 2020;Rocha and Fellowes 2020) and even rainfall (Lowe et al 2017) at a regional level can influence arthropod abundance, richness and communities such as the ones included in this study. Furthermore, different species react differently to different environmental disturbances and mechanisms (Rocha and Fellowes 2020), thus influencing the patterns and trends we observe.…”

“…The general consensus seems to be that urbanization negatively influences arthropod predators compared to rural or peri-urban environments with less effects of urbanization (Fenoglio et al 2020;Rocha and Fellowes 2020;Koranyi et al 2021). Peri-urban rangelands and urban environments share species but the communities with these environments differ.…”

History of the Biodiversity of Ladybirds (Coccinellidae) at the Black Sea Coast of the Russian Caucasus in the Last 120 Years—Does the Landscape Transformation and Establishment of Harmonia axyridis Have an Impact?

“…Twenty-nine of these species still occurred in the region in 1990–2020. Therefore, landscape transformation and intensive recreational use for several decades have not caused the large-scale extinction of native ladybird species, corresponding to the fact that many ladybird species successfully adapt to urbanization [ 46 ].…”