Predators, parasitoids and pathogens: species richness, trophic generality and body sizes in a natural food web

By J. Memmott, Neo D. Martinez, Joel E. Cohen. 2000

299 citations recorded by the source corpus.

Summary 1. A food web is presented which describes trophic interactions among the herbivores, parasitoids, predators and pathogens associated with broom, Cytisus scoparius (L.) Link. The data come from published work on the community at a single site. The web comprises a total of 154 taxa: one plant, 19 herbivores, 66 parasitoids, 60 predators, five omnivores and three pathogens. There are 370 trophic links between these taxa in the web. The taxa form 82 functionally distinct groups, called trophic species. 2. Predators consumed significantly more species than did parasitoids: a median of two prey species per species of predator (range = 1–9), compared to a median of one host species per species of parasitoid (range = 1–4). Significant differences in the number of species consumed were also found among the five predator groups: birds (median = 4), spiders (median = 5), Coleoptera (median = 1), Diptera (median = 2) and Hemiptera (median = 7). 3. Vulnerability, measured by numbers of consumer species, was significantly affected by the herbivores’ feeding styles: externally feeding herbivores were most vulnerable and the concealed herbivores were least vulnerable. Miners were vulnerable to the most parasitoid species and externally feeding herbivores were the most vulnerable to predators. 4. Resource species had a median vulnerability of 13 consumer species, a figure far higher than that in most published food webs. No significant relationship was found between species’ vulnerability to predators and vulnerability to parasitoids. However, there was a strong negative relationship between the percentage mortality due to predation and percentage mortality due to parasitism. 5. The broom food web contains nine orders of insects, a figure higher than previously recorded. The web also contains vertebrates, arachnids, bacteria and fungi. Most of the interactions between the orders were weak. Connectance was calculated for the complete web, the parasitoid sub-web and the predator sub-web. The connectance of the predator sub-web, a value of 0·0364, was more than an order of magnitude larger than the connectance of the entire web (0·0156) or the parasitoid sub-web (0·018). 6. The body lengths of 52 species in the food web were estimated from field guides or museum specimens. Larger predators consumed smaller prey in 93% of predator–prey interactions. Smaller parasitoids consumed larger hosts in 79% of parasitoid–host interactions. Parasitoids were significantly smaller than predators. 7. The 52 species were arranged in order of increasing body length along the columns and down the rows of a food web matrix. The predator sub-web was predominantly upper triangular with 8% of non-zero elements falling below the leading diagonal. The parasitoid sub-web was predominantly lower triangular with 21% non-zero elements falling above the leading diagonal. The entire web contains entries both above and below the main diagonal and thus violates a central assumption of the cascade model.

Subfields: Ecology, Evolution, Behavior and Systematics, Insect Science, Plant Science

View Paper: https://www.semanticscholar.org/paper/a1b19dfea556c213d3caa066a90bbcdfd903fb80

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Ecology, Evolution, Behavior and Systematics

In Insect Science

In Plant Science

Citations in the corpus

The signature of phylogenetic constraints on food-web structure (2008, unknown): “…et al. (2005), which encompasses 16,863 records of trophic interactions from 10 food-web studies (Warren, 1989; Dawah et al., 1995; Yodzis, 1998; Memmott et al., 2000; Cattin Blandenier, 2004; Woodward et al., 2005; Jonsson et al., 2005; Harper-Smith et al., 2005; Ledger, Edwards, and Woodward,…”
Body size and trophic position in a temperate estuarine food web (2008, background): “Many ecologists have suggested that body size can influence trophic hierarchies (Warren and Lawton, 1987; Lawton, 1989; Cohen et al., 1993; Memmott et al., 2000; Neubert et al., 2000; Woodward and Hildrew, 2002).”
Small world patterns in food webs. (2000, unknown): “Silwood park web (Memmott et al., 2000): this is a sub-web obtained from a field site of 97 hectares in size.”
Food webs and parasites in a salt marsh ecosystem. (2006, background): “This was the case for the parasitoid-host subwebs of Memmott et al. (2000), which had low connectance due to high host specificity.”
Characterization of topological keystone species: Local, global and “meso-scale” centralities in food webs (2007, background): “Scotch Broom (N = 154, E = 366) contains trophic interactions between the herbivores, parasitoids, predators and pathogens associated with broom, Cytisus scoparius, collected in Silwood Park, Berkshire, England, UK (Memmott et al., 2000).”
FOOD WEB COHESION (2004, background): “…1989; St. Martin (STM), Goldwasser and Roughgarden 1993; United Kingdom Grassland (UKG), Martinez et al. 1999; Ythan Estuary (YE), Huxam et al. 1996; Silwood Park (SP), Memmott et al. 2000; El Verde (EV), Reagan and Waide 1996; Little Rock Lake (LRL), Martinez 1991; and Caribbean Coral Reef…”
Food‐web assembly during a classic biogeographic study: species’“trophic breadth” corresponds to colonization order (2008, background): “Food-web theory uses a conceptual map of who eats whom among species to describe diversity patterns within local assemblages (Schoener 1989, May 1973, Dunne 2006).”
The Structure of Plant-Animal Mutualistic Networks (2006, background): “…in four cases out of 66 studied by Bascompte et al. (2003), all four corresponding to parasitoid food webs: seed feeder miner-parasitoids in Silwood Park (Memmott et al. 2000), and grass-herbivores, insect-parasitoids, and parasitoids-hiperparasitoids in Grass Stems, U.K. (Martinez et al. 1999).”
Topological properties of food webs: from real data to community assembly models Oikos 102 (2003, background): “All are community food webs with the exception of Silwood Park, which is a source food web (Cohen et al. 1990, Memmott et al. 2000), and the UK grassland parasitoid assemblage, which is a composite web from, different sites (Cohen et al. 1990, Dawah et al. 1995).”
Seeing Double:: Size-Based and Taxonomic Views of Food Web Structure (2011, background): “, 2011; Vezina, 1985), while others have examined patterns within a single, local food web (Cohen, 2007; Cohen et al., 2003; de Visser et al., 2011; Jacob et al., 2011; Leaper and Huxham, 2002; McLaughlin et al., 2010; Memmott et al., 2000; O’Gorman and Emmerson, 2010; Warren and Lawton, 1987; Yvon-”
Network structure and biodiversity loss in food webs: robustness increases with connectance (2002, methodology): “” Memmott et al. (2000) compiled the food web by starting with the shrub Scotch broom and tracing herbivore, predator, parasitoid, and pathogen trophic links upward from that plant species, ignoring pathways leading to other basal species present in the community.”
DETERMINANTS OF PARASITOID–HOST ASSOCIATIONS: INSIGHTS FROM A NATURAL TACHINID–LEPIDOPTERAN COMMUNITY (2003, background): “Vulnerability of insect herbivores to predators and parasitoids were negatively associated in the few studies yet to examine this issue (Dyer and Gentry 1999, Memmott et al. 2000).”