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Research article - Peer-reviewed, 2016

Diagnostic PCR assays to unravel food web interactions in cereal crops with focus on biological control of aphids

Staudacher, Karin; Jonsson, Mattias; Traugott, Michael


Successful biological control of agricultural pests is dependent on a thorough understanding of the underlying trophic interactions between predators and prey. Studying trophic interactions can be challenging, particularly when generalist predators that frequently use multiple prey and interact with both pest and alternative prey are considered. In this context, diagnostic PCR proved to be a suitable approach, however at present, prey-specific PCR primers necessary for assessing such interactions across trophic levels are missing. Here we present a new set of 45 primers designed to target a wide range of invertebrate taxa common to temperate cereal crops: cereal aphids, their natural enemies such as carabid beetles, ladybeetles, lacewings, and spiders, and potential alternative prey groups (earthworms, springtails, and dipterans). These primers were combined in three 'ready to use' multiplex PCR assays for quick and cost-effective analyses of large numbers of predator samples. The assays were tested on 560 carabids collected in barley fields in Sweden. Results from this screening suggest that aphids constitute a major food source for carabids in cereal crops (overall DNA detection rate: 51 %), whereas alternative extraguild and intraguild prey appear to be less frequently preyed upon when aphids are present (11 % for springtails and 12 % for earthworms; 1 % for spiders and 4 % for carabids). In summary, the newly developed molecular assays proved reliable and effective in assessing previously cryptic predator-prey trophic interactions, specifically with focus on biological control of aphids. The diagnostic PCR assays will be applicable manifold as the targeted invertebrates are common to many agricultural systems of the temperate region.


Molecular gut content analysis; Group-specific primer; Multiplex PCR; Generalist predators; Carabid beetles

Published in

Journal of Pest Science
2016, volume: 89, number: 1, pages: 281-293

Authors' information

Staudacher, Karin
University of Innsbruck
Swedish University of Agricultural Sciences, Department of Ecology
Traugott, Michael
University of Innsbruck

Associated SLU-program

SLU Network Plant Protection

UKÄ Subject classification


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