Urbanisation and forest size affect the infestation rates of plant-galling arthropods and damage by herbivorous insects

Abstract

http://www.eje.cz in butterfl ies (Di Mauro et al., 2007). Martinson & Raupp (2013) reported a decrease in species richness in carabid beetles, particularly in large, predatory and poor dispersing species and those that have strict habitat requirements. However, in the same meta-analysis, Martinson & Raupp (2013) reported an overall neutral effect of urbanisation on coleopteran herbivores, but a negative effect on the tiny herbivores in this insect order. In contrast, several studies showed that urbanisation increased the abundances and infestation rates of herbivorous arthropods (Christie & Hochuli, 2005; Raupp et al., 2010). A major aspect of urbanisation is the fragmentation of natural and semi-natural habitats (Marzluff et al., 2008; Raupp et al., 2010). Some meta-analyses reveal an overall lower level of damage by herbivorous insects in fragments (Martinson & Fagan, 2014), whereas others reported a neutral effect on overall herbivory (Rossetti et al. 2017). Fragmented forests also seem to be subjected to more pronounced edge effects than other semi-natural habitats (Marzluff et al., 2008; Dale & Frank 2014). This assumption was confi rmed by several studies, which reported both a higher abundance and species richness of herbivorous arthropods and thus a higher extent of leaf damage in forest edges than in the forest interior (Christie & Hochuli, 2005; Guimarães et al., 2014).

Two galling insects (Hartigiola annulipes and Mikiola fagi), one host plant (Fagus sylvatica) – differences between leaf and gall chemical composition

“…The stand environmental conditions, including the tree-species combination and chemical properties of soil, may affect various traits of tree organs, nutrient turnover, as well as the spatial distribution and number of galls (Nicolai 1988, Balsberg Påhlsson 1989, Veldtman and Mc-Geoch 2003, Castellanos et al 2006, Forey et al 2016, Meyer et al 2020. Although this study was conducted in two different forest stands, the SLA comparison, which is a useful parameter reflecting light conditions, showed no differences between stands.…”

Herbivory on the pedunculate oak along urbanization range in Europe: effects of local forest cover and insect feeding guild

“…Herbivory varied with canopy cover in the immediate vicinity of oaks, but this effect was guild specific: there was an independent positive effect of local canopy cover on herbivory, a negative effect on gall-inducing herbivores, and no effect on leaf-mining herbivores. Whereas several studies have compared herbivore abundance or diversity, and sometimes herbivory, between urban and forested environments (Herrmann et al, 2012;Kozlov et al, 2017;Moreira et al, 2019), only a handful of them have addressed the effect of urban tree density on insect herbivores (Barr et al, 2021;Christie et al, 2010;Christie and Hochuli, 2005;Herrmann et al, 2012;Long and Frank, 2020;Meyer et al, 2020;Raupp et al, 2010). Their findings were contradictory with reports of both higher (Christie and Hochuli, 2005) and lower (Herrmann et al, 2012;Long and Frank, 2020) herbivory in isolated trees as compared to trees growing in larger forest patches.…”

“…We defined the degree of urbanization around focal trees as the percentage of impervious surface (including roads and buildings) in a buffer with a radius of 200 m centered on the focal oaks based on oak coordinates as retrieved from Google Maps by project partners (Meyer et al, 2020;Parsons and Frank, 2019). We also calculated the percentage of local canopy cover within a 20 m buffer (excluding open areas and grasslands).…”

“…We also calculated the percentage of local canopy cover within a 20 m buffer (excluding open areas and grasslands). We used this buffer size of local canopy cover because the local abundance of trees is a strong driver of urban biodiversity (Herrmann et al, 2012;Long and Frank, 2020;Meyer et al, 2020;Parsons and Frank, 2019;Stemmelen et al, 2020). To that aim we used the High Resolution Layers of the CORINE land cover datasets with 10 m resolution and with reference year 2018 (± 1 year).…”

“…Second, cities differ greatly in the amount of vegetation they harbour. The local tree cover (i.e., both overall tree density and potential host tree abundance) is a strong driver of urban biodiversity and trophic interactions between trees, insect herbivores and their enemies (Herrmann et al, 2012;Long and Frank, 2020;Meyer et al, 2020;Stemmelen et al, 2020). More isolated trees frequently offer fewer resources to insect herbivores (Chavez-Pesqueira et al, 2015), leading to a decrease in insect herbivory (Long and Frank, 2020).…”