Effects of Wildflower Strips and an Adjacent Forest on Aphids and Their Natural Enemies in a Pea Field.

Séverin Hatt,Pierre Mouchon,Thomas Lopes,Frédéric Francis

doi:10.3390/insects8030099

Séverin Hatt, Pierre Mouchon + Show 2 more

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https://doi.org/10.3390/insects8030099

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Journal: Insects	Publication Date: Sep 13, 2017
Citations: 12	License type: CC BY 4.0

Affiliation: Gembloux Agro-Bio Tech, University of Liège, JUNIA

Abstract

Landscape diversification is a key element for the development of sustainable agriculture. This study explores whether the implementation of habitats for pest natural enemies enhances conservation biological control in an adjacent field. In the present study conducted in Gembloux (Belgium) in 2016, the effect of two different habitats (wildflower strips and a forest) and aphid abundance on the density of aphid natural enemies, mummified aphids and parasitism on pea plants was assessed through visual observations. The effect of the habitats on aphids was also evaluated. The habitats but not aphid density significantly affected hoverfly larvae, which were more abundant adjacent to wildflower strips than to the forest. The contrary was observed for ladybeetle adults, which were positively related with aphids but not affected by the adjacent habitats. The abundance of mummies and the parasitism rate were significantly affected by both the habitats and aphid density. They were both significantly enhanced adjacent to wildflower strips compared to the forest, but the total parasitism rate was low (<1%), questioning whether parasitoids could significantly control aphids on the pea crop. As for the aphids, their abundance was not significantly affected by the adjacent habitats. These results are discussed with respect to the potential of these habitats to provide overwintering sites and food resources for natural enemies, and thereby enhance conservation biological control.

Highlights

The adoption of intensive agricultural practices in Europe has led to a simplification of agricultural landscapes and an increased use of external inputs, among others insecticides [1]
By focusing on wildflower strips (WFS) and a forest, the present study aims at answering the following questions: (i) Do WFS and forests differently affect the abundance of aphids and their natural enemies, as well as parasitism, in the adjacent crop? (ii) Does aphid density—compared to habitats—drive natural enemy spread in fields?
The opposite was observed for ladybeetle adults, which were positively correlated with aphids but not affected by the adjacent habitats (Table 1 and Figure 2c)

Summary

Introduction

The adoption of intensive agricultural practices in Europe has led to a simplification of agricultural landscapes and an increased use of external inputs, among others insecticides [1]. Insects 2017, 8, 99 parasitoids, overwintering sites and shelters against disturbances [10] Their implementation and management is subsidised in many European countries through agri-environmental policies, in order to “reduce environmental risks associated with modern farming on the one hand, and preserve nature and cultivated landscapes on the other hand” [11]. Their potential benefits for CBC have been reviewed [12].

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