Proportion of Grassland at Landscape Scale Drives Natural Pest Control Services in Agricultural Landscapes

Thomas Perrot,Sabrina Gaba,Vincent Bretagnolle,Camille Coux,Adrien Rusch

doi:10.3389/fevo.2021.607023

Abstract

Managing regulating ecosystem services delivered by biodiversity in farmland is a way to maintain crop yields while reducing the use of agrochemicals. Because semi-natural habitats provide shelter and food for pest enemies, a higher proportion of semi-natural habitats in the landscape or their proximity to crops may enhance pest control in arable fields. However, the ways in which the spatial arrangement of these habitats affects the delivery of this beneficial ecosystem service to crops remains poorly known. Here, we investigated the relative effects of the amount of grassland in the landscape versus the distance to the nearest grassland on the predation rates of weed seeds and aphids into 52 cereal fields. We found that both seed and aphid predation levels increased with the proportion of grassland in a 500 m radius buffer while the distance to the nearest grassland displayed no effect. We show that increasing from 0 to 50% the proportion of grasslands in a 500 m radius, respectively, increased seed and aphid predation by 38 and 20%. In addition to the strong effect of the proportion of grassland, we found that seed predation increased with the proportion of forest fragments while aphid predation increased with the proportion of organic farming in the landscape. Overall, our results reveal that natural pest control in cereal crops is not related to the distance to the nearest grassland, suggesting that natural enemies are not limited by their dispersal ability. Our study indicates that maintaining key semi-natural habitats, such as grasslands, is needed to ensure natural pest control and support food production in agricultural landscapes.

Highlights

Agricultural intensification, which manifests through a massive use of pesticides, low crop diversity or landscape simplification, has major impacts on biodiversity (Beketov et al, 2013; Maxwell et al, 2016)
Seed predation rate was in average of 0.42 ± 0.29 while aphid predation rate was 0.81 ± 0.24
Effect of grassland was similar between models with landscape variables estimated at 500 and 750 m (Table 2 and Supplementary Table 1), but models with landscape variables calculated at 500 m had lowest Akaike Information Criterion (AIC) for both aphid and seed, were chosen

Summary

Introduction

Agricultural intensification, which manifests through a massive use of pesticides, low crop diversity or landscape simplification, has major impacts on biodiversity (Beketov et al, 2013; Maxwell et al, 2016). A large body of research has focused on understanding the mechanisms operating at multiple spatial scales, from the plant to the landscape, driving the presence of natural enemies and the level of pest suppression in agroecosystems (Bianchi et al, 2006; Rusch et al, 2010, 2016; Chaplin-Kramer et al, 2011) While these studies have demonstrated that landscape heterogeneity is a major predictor of the level of natural pest control, the relative importance of landscape composition (i.e., amount of habitats) and of its configuration (i.e., spatial arrangement of habitats) on this key function remains poorly explored (but see Martin et al, 2019)

Objectives

Methods

Results

Discussion

Conclusion