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Is there a synergy between hedges and intercrops for pest biocontrol ?

Alignier, Audrey and Andrieu, Emilie and Bedoussac, Laurent and Journet, Etienne-Pascal and Ouin, Annie and Sarthou, Jean-Pierre and Vialatte, Aude and Brin, Antoine Is there a synergy between hedges and intercrops for pest biocontrol ? (2013) In: 11th International Association Ecology Congress - INTECOL 2013, 18 August 2013 - 23 August 2013 (Londres, United Kingdom).

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Abstract

A major challenge for agroecology is to identify alternative cropping systems that can both ensure sufficient levels of food production and reduction in pesticide inputs while maintaining ecosystem integrity and simultaneously delivering multiple ecosystem services. Among ecological services, biocontrol of pests by natural enemies could be improved by effective management of semi-natural elements in landscape such as hedgerows (Landis et al., 2000). Another way to reduce pest populations in fields consists in increasing diversity of crop species both in time and space. A practice such as intercropping that creates structures of mixed plant populations with "barrier" or "dilution of resources" effects (Médiène et al., 2011) can reduce the pressure of pathogens, weeds and pests compared with that exerted on sole crops (Letourneau et al., 2011). While the combination of these two kinds of practices designed to strengthen auxiliary communities often appears efficient and could result in a synergy, many cases of study show opposite results (e.g. Straub and Snyder, 2006). Our study aimed at quantifying and comparing the efficiency of both hedgerow and intercropped pea and wheat on pest biocontrol in a field. We examined i) the potential role of different types of field edges (with and without an hedgerow) on biological control of weed seeds, aphids, pea weavils and eggs of Sitona lineatus, ii) the effect of intercropping on the biological control of these pests compared with sole crops and iii) the interaction between the two factors. We conducted both field surveys of pest abundance and pest biocontrol effectiveness by estimating predation rates by using seeds and prey sticked on cards. We found that aphid density was slightly lower in pea-wheat intercrops than in sole crops, and was influenced by the distance from the field edge (whatever the kind of edges). However, neither the hedgerow nor the intercrop situation favored aphid predation. The density of weeds did not vary according to the cropping system and distance from the field edge. We showed that the predation rate of weed seeds or of Sitona lineatus eggs and the parasitism of Bruchus pisorum decreased according to the distance to the hedge in sole crops but increased in the intercrop. This study points out the absence of a global synergy between intercrops and hedges in supporting pest and weed regulation: the regulation efficiency varied according to pest species. This study calls for a deepened multi-species approach in order to find trade-offs between agricultural practices and field edge management to optimize regulating ecosystem services such as pest biocontrol.

Item Type:Conference or Workshop Item (Poster)
Additional Information:Thanks to the ⓒ INTECOL Association.
ProdINRA Id:387427
Audience (conference):International conference without published proceedings
Uncontrolled Keywords:
Institution:Université de Toulouse > Ecole Nationale Supérieure de Formation de l'Enseignement Agricole - ENSFEA (FRANCE)
Université de Toulouse > Ecole d'Ingénieurs de Purpan - EIP (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
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Deposited By: INRA INRA
Deposited On:24 May 2017 11:51

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