Spatiotemporal variations in aphid‐parasitoid relative abundance patterns and food webs in agricultural ecosystems

Thiago Oliveira Andrade,Aude Vialatte,Yannick Outreman,Liliane Krespi,Bertrand Gauffre,Manuel Plantegenest,Joan Van Baaren

doi:10.1890/es15-00010.1

Abstract

Understanding the stability of communities is fundamental in theoretical and applied ecology. Organisms atop trophic chains are particularly sensitive to disturbance, especially when they are dependent on a specific trophic resource subject to strong fluctuations in density and quality, which is the case of parasitoids. We investigated the (1) variability in spatiotemporal relative abundance patterns of a cereal aphid parasitoid community, determining at what scales such patterns vary in agrosystems. We also investigated whether (2) parasitoid relative abundances are strongly influenced by host relative abundances and if (3) different host species are exploited at distinct rates. Aphid parasitoid populations were monitored in three remote agricultural regions in France between 2010 and 2012. Five parasitoid species (Hymenoptera: Braconidae: Aphidiinae) and three aphid species (Hemiptera: Aphididae) were identified in each of those three regions. Fields sampled in one region in a single year exhibited similar relative abundance patterns, with aphid parasitoid communities varying across regions and years. All parasitoid species were able to exploit each monitored host species. Metopolophium dirhodum Wlk was consistently a more frequent species among parasitized aphids than among living aphids, indicating that this aphid species was exploited at a higher rate than the other two aphid species found (Sitobion avenae F and Rhopalosiphum padi L). Those findings suggest the cereal aphid‐parasitoid network is not strictly determined by the intrinsic permanent environmental characteristics but partially varies from one year to another. The similarity in abundance patterns in different fields of a region in a given year suggests the existence of a mechanism allowing a rapid synchronisation of the relative abundance patterns at an intra‐regional scale. This phenomenon could be useful in predicting host‐parasitoid communities and bear important consequences for the ecosystem service provided by parasitoids.

Highlights

Evaluating the importance of factors that drive the structure of communities is an important objective of both theoretical and applied ecology (Nowicki et al 2009)
We investigated the (1) variability in spatiotemporal relative abundance patterns of a cereal aphid parasitoid community, determining at what scales such patterns vary in agrosystems
We investigated whether (2) parasitoid relative abundances are strongly influenced by host relative abundances and if (3) different host species are exploited at distinct rates

Summary

Introduction

Evaluating the importance of factors that drive the structure of communities is an important objective of both theoretical and applied ecology (Nowicki et al 2009). Several studies have focused on the influence of land cover patterns (Coll and Hopper 2001, Kruess 2003, Costamagna et al 2004, Bennett and Gratton 2012) or climate (Stireman et al 2005) on the species richness, abundance and diversity of parasitoid communities (Folcher et al 2011), but few studies have considered the large scale spatiotemporal variations in their relative abundances (e.g., Holler 1990, Gomez and Zamora 1994, Le Corff et al 2000) Such investigation would help determining the extent to which environmental factors affect parasitoid communities and understanding the spatiotemporal dynamics of those organisms

Methods

Results

Conclusion