A hierarchical multi‐scale analysis of the spatial relationship between parasitism and host density in urban habitats

Fenoglio, María Silvina; Werenkraut, Victoria; Morales, Juan Manuel; Salvo, Adriana

doi:10.1111/aec.12491

Cited by 4 publications

(3 citation statements)

References 82 publications

(209 reference statements)

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“…Urbanisation has been shown to negatively affect the persistence, performance and behaviour of parasitoid species and at the same time, the structure of parasitoid communities (Bennett & Gratton, 2012; Bergerot et al, 2010; Corcos et al, 2019; Fenoglio & Salvo, 2010; Gardiner & Harwood, 2017; Nelson & Forbes, 2014), which in turn could influence parasitism rates. Moreover, urbanisation can affect prey availability, which may ultimately impact parasitism rates (Fenoglio et al, 2017). The effect of prey density on parasitism can also depend on the scale.…”

Section: Introductionmentioning

confidence: 99%

Living in an urban pod: Seed predation and parasitism of bruchid beetles in a native tree species

Galfrascoli

Calviño

Chiapero

et al. 2022

Ecological Entomology

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1. Urbanisation is one of the main drivers of insect species loss worldwide. However, its impacts on ecological interactions involving insects still deserve further research, especially seed predation and parasitism of seed predators.2. Here, we evaluated the seed predation rate by the specialist bruchid beetle Pseudopachymerina spinipes and its parasitism rate in the native tree Vachellia caven (Fabaceae) along an urbanisation gradient in Cordoba (Argentina). Since resource availability can influence these ecological interactions, we also investigated whether seed and prey availability could affect seed predation and parasitism rates, respectively.3. We sampled trees in 10 sampling sites along an urbanisation gradient estimated by the Normalised Difference Vegetation Index (NDVI) within a 100 m radius. In our system, sites with low NDVI, beyond representing the low amount of vegetation cover, also indicate high surface temperature and low availability of host trees.4. Seed predation in V. caven and the parasitism rate of P. spinipes were significantly reduced with increasing urbanisation. Notably, seed availability at the pod level did not affect seed predation rate, while prey availability was negatively correlated with parasitism rate. 5. These findings suggest a deleterious effect of urbanisation on the studied antagonistic interactions, giving no support to the idea of resource limitation effects.

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Section: Introductionmentioning

confidence: 99%

Living in an urban pod: Seed predation and parasitism of bruchid beetles in a native tree species

Galfrascoli

Calviño

Chiapero

et al. 2022

Ecological Entomology

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“…We calculated four different measures of parasitism for each host species: (1) presence or absence of parasitism per site, (2) proportion of sampled B. oleracea plants with parasitized hosts, (3) presence or absence of parasitism per host individual, and (4) proportion of parasitized hosts. These measures consider parasitism at multiple scales, reflecting parasitoid foraging decisions at the site, plant, and host levels, as well as the impact of parasitism on the host population (Fenoglio et al, 2017). The presence of parasitism per site is a coarse measure indicating whether parasitoids have sufficiently colonized a given site and is likely informed by habitat quality, such as host density and floral resources, as well as the connectivity of the surrounding landscape (Kruess & Tscharntke, 1994; Tentelier & Fauvergue, 2007).…”

Section: Methodsmentioning

confidence: 99%

Shifts in host–parasitoid networks across community garden management and urban landscape gradients

Lucatero,

Smith,

Bichier

et al. 2024

Ecosphere

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Biological pest control relies on interactions between herbivores and their natural enemies. Maintaining this ecosystem service requires considering herbivore and natural enemy interactions and their response to anthropogenic change at multiple scales. In this study, we used ecological networks to quantify the network structure of interactions between herbivorous insects and their parasitoids. We examined how herbivore host abundance, parasitism rates, and shifts in network structure relate to changes in local habitat management and landscape context. We sampled herbivores and parasitoids in Brassica oleracea plants at 22 urban gardens in the Central Coast of California. At each site, we measured local management characteristics (e.g., vegetation, ground cover, canopy cover) and quantified surrounding landscape composition (e.g., urban, natural, open, and agricultural cover). For the eight sites with large enough networks, we calculated three network structure metrics (interaction richness, vulnerability, and functional complementarity). We then used generalized linear and mixed models to examine relationships between herbivore host abundance, parasitism rates, garden management and landscape characteristics, and network metrics. We found that both local management and landscape composition influenced parasitism, while only local factors affected host abundance and network structure. Higher network interaction richness was marginally associated with enhanced parasitism rates for two host species and lower parasitism rates for one host species. Our results suggest that local garden management decisions may shift the structure of host–parasitoid networks, which may subsequently affect host parasitism rates, but outcomes for biological pest control will likely vary across host species.

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“…Environmental factors such as local vegetation composition and complexity, as well as the amount of impervious cover (i.e., concrete and built surfaces) in the urban landscape can directly and indirectly affect higher trophic interactions like parasitism of herbivores across spatial scales (PereiraPeixoto, Pufal, Staab, Martins, & Klein, 2016;Fenoglio, Werenkraut, Morales, & Salvo, 2017). For example, as predicted by the resource concentration hypothesis (Root, 1973), high host plant density in urban yards and parks increases the likelihood of pest outbreaks by directly increasing resource availability for herbivores (Dreistadt, Dahlsten, & Frankie, 1990;Shrewsbury & Raupp, 2006;Shrewsbury & Raupp, 2000).…”

Section: Introductionmentioning

confidence: 99%

Herbivore regulation in urban agroecosystems: Direct and indirect effects

Egerer

Liere

Lin

et al. 2018

Basic and Applied Ecology

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Urban agroecosystems can provide habitat for biodiversity and can benefit human communities through urban food provisioning. Moreover, urban agroecosystems could be managed so as to optimize ecosystem services like natural pest control provided by trophic interactions between natural enemies and herbivores. As in other ecosystems, predation and parasitism regulate herbivores in urban settings, but less is known about the relative importance of direct and indirect effects at local and landscape scales in highly managed urban agroecosystems. We collected data on herbivore (cabbage aphid) density and parasitism ratios (proportion of parasitized aphid "mummies") in 25 community gardens in three counties in the California central coast, USA. We used structural equation modeling to examine the effects of direct factors (host plant characteristics and parasitism) and indirect factors (soil, garden, and landscape characteristics) on herbivore density changes at two time points in the growing season (June and August). Aphid density, but not parasitism, varied across counties over the season, and there was a strong negative relationship between aphid density and parasitism. Direct effects were strong drivers of aphid density but not parasitism. In June, aphid density increased with host plant volume but decreased with greater floral density, while parasitism was only influenced by aphid density. In August, host plant volume similarly positively affected aphid density, and soil water holding capacity increased host plant volume. In addition, host plant density had a strong negative effect on parasitism. Urban gardeners may be able to reduce aphid pest densities by increasing floral resource density and strategically spatially distributing host plants throughout garden beds, though these processes depend on the season. The indirect effects of soil water holding capacity on aphid densities further suggest a critical role of human management on pest populations and pest control services through soil amendments and irrigation.

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A hierarchical multi‐scale analysis of the spatial relationship between parasitism and host density in urban habitats

Cited by 4 publications

References 82 publications

Living in an urban pod: Seed predation and parasitism of bruchid beetles in a native tree species

Living in an urban pod: Seed predation and parasitism of bruchid beetles in a native tree species

Shifts in host–parasitoid networks across community garden management and urban landscape gradients

Herbivore regulation in urban agroecosystems: Direct and indirect effects

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