Research article - Peer-reviewed, 2017
Diet of generalist predators reflects effects of cropping period and farming system on extra- and intraguild prey
Roubinet, Eve; Birkhofer, Klaus; Malsher, Gerard; Staudacher, Karin; Ekbom, Barbara; Traugott, Michael; Jonsson, MattiasAbstract
The suppression of agricultural pests by natural enemies, including generalist arthropod predators, is an economically important regulating ecosystem service. Besides pests, generalist predators may also consume non-pest extraguild and intraguild prey, which can affect their impact on pest populations. This may either reduce the impact of generalist predators on pest populations, because they are diverted from pest predation, or increase it, as it helps them survive periods of low pest availability. However, the availability of pest prey and alternative, non-pest prey can vary over the crop growing season and between farming systems, potentially affecting predator-prey interactions and the levels of biological control. We have limited information about how farming systems and environmental variation over the crop growing season influence predator diets. This limits our ability to predict the importance of generalist predators as natural enemies of agricultural pests. Here we utilize molecular gut content analyses to assess detection frequencies of extra-and intraguild prey DNA in generalist predator communities in replicated organically and conventionally managed cereal fields at two key periods of the cropping season for aphid biological control. This is done in order to understand how farming system, crop season, prey availability and predator community -composition determine the composition of predator diets. Aphid pests and decomposers (springtails) were equally important prey for generalist predators early in the growing season. Later in the season, the importance of aphid prey increased with increasing aphid densities while springtail predation rates were positively correlated to abundance of this prey at both early and late crop growth stages. Intraguild predation was unidirectional: carabids fed on spiders, whereas spiders rarely fed on carabids. Carabids had higher detection frequencies for the two most common spider families in organically compared to conventionally managed fields. Our study documents that predation by generalist predator communities on aphid pests increases with pest numbers independently of their generally widespread consumption of alternative, non-pest prey. Therefore, conservation strategies in agricultural fields could promote biological control services by promoting high levels of alternative non-pest prey for generalist predator communities.Keywords
aphids; Araneae; biological control; Carabidae; intraguild predation; molecular gut content analyses; organic farmingPublished in
Ecological Applications2017, volume: 27, number: 4, pages: 1167-1177
Publisher: WILEY
Authors' information
Roubinet, Eve
Swedish University of Agricultural Sciences, Department of Ecology
Birkhofer, Klaus
Brandenburg University of Technology (BTU) Cottbus – Senftenberg
Swedish University of Agricultural Sciences, Department of Ecology
Staudacher, Karin
University of Innsbruck
Ekbom, Barbara
Swedish University of Agricultural Sciences, Department of Ecology
Traugott, Michael
University of Innsbruck
Swedish University of Agricultural Sciences, Department of Ecology
Associated SLU-program
SLU Network Plant Protection
UKÄ Subject classification
Ecology
Publication Identifiers
DOI: https://doi.org/10.1002/eap.1510
URI (permanent link to this page)
https://res.slu.se/id/publ/90677