The ubiquity of intraguild predation among predatory arthropods.

Annie-Ève Gagnon,Jacques Brodeur,George E Heimpel,Attila Szolnoki

doi:10.1371/journal.pone.0028061

Annie-Ève Gagnon, Jacques Brodeur + Show 2 more

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https://doi.org/10.1371/journal.pone.0028061

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Abstract

Intraguild predation (IGP) occurs when one predator species attacks another predator species with which it competes for a shared prey species. Despite the apparent omnipresence of intraguild interactions in natural and managed ecosystems, very few studies have quantified rates of IGP in various taxa under field conditions. We used molecular analyses of gut contents to assess the nature and incidence of IGP among four species of coccinellid predators in soybean fields. Over half of the 368 predator individuals collected in soybean contained the DNA of other coccinellid species indicating that IGP was very common at our field site. Furthermore, 13.2% of the sampled individuals contained two and even three other coccinellid species in their gut. The interaction was reciprocal, as each of the four coccinellid species has the capacity to feed on the others. To our knowledge, this study represents the most convincing field evidence of a high prevalence of IGP among predatory arthropods. The finding has important implications for conservation biology and biological control.

Highlights

According to an analysis conducted by Arim and Marquet [12] using 113 food webs, 58– 87% of animal species are involved in intraguild predation (IGP) interactions
Using raw data leads to an underestimation of the relative importance of IGP by H. axyridis and C. septempunctata
Our results indicate that IGP is very common among coccinellid species in soybean fields

Summary

Introduction

Communities involve thousands of species interacting in many diverse ways within the spatial and temporal variability of natural ecosystems [1]. Following the pioneering field study of Polis and McCormick [4] on species of desert scorpions that feed on each other, a fertile and rapidly growing literature on IGP has led to a reconsideration of several classical topics in ecology such as stability and diversity of communities, trophic cascades in food webs, niche shift and species exclusion, as well as the effects of ecosystem productivity on species interactions [3,5,6,7,8]. According to an analysis conducted by Arim and Marquet [12] using 113 food webs, 58– 87% of animal species are involved in IGP interactions

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