Present address: J.F. Blumenbach Institute of Zoology and Anthropology, University of Goettingen, Berliner Str. 28, 37073 Goettingen, Germany.
Which prey sustains cold-adapted invertebrate generalist predators in arable land? Examining prey choices by molecular gut-content analysis
Article first published online: 18 JAN 2011
© 2011 The Authors. Journal of Applied Ecology © 2011 British Ecological Society
Journal of Applied Ecology
Volume 48, Issue 3, pages 591–599, June 2011
How to Cite
Eitzinger, B. and Traugott, M. (2011), Which prey sustains cold-adapted invertebrate generalist predators in arable land? Examining prey choices by molecular gut-content analysis. Journal of Applied Ecology, 48: 591–599. doi: 10.1111/j.1365-2664.2010.01947.x
- Issue published online: 13 MAY 2011
- Article first published online: 18 JAN 2011
- Received 20 July 2010; accepted 16 December 2010, Handling Editor: Joan Cossentine
- conservation biological control;
- detrital subsidy;
- intraguild predation;
- multiplex PCR
1. Generalist predators such as carabid and cantharid beetles form an important component within natural enemy communities in arable land. Usually, predator–prey interactions are examined during the vegetation period, largely ignoring food web interactions occurring in the cold season. This is, however, when the larval stages of many polyphagous beetles develop whose survival critically depends on the availability of suitable prey.
2. In this study, we examined intra- and extraguild feeding links in larval Cantharis spp. (Coleoptera: Cantharidae) and Nebria brevicollis (Coleoptera: Carabidae), both abundant cold-adapted invertebrate predators in European arable land. As these immature beetles are fluid feeders, which impedes a microscopic analysis of their gut content, multiplex polymerase chain reaction assays were developed to examine trophic linkages in the field.
3. Collembolan DNA was detected in 49% and 54% of cantharid and carabid larvae, respectively. Earthworms were consumed by 34% of cantharid and 24% of carabid larvae. Significant differences in lumbricid and collembolan prey detection rates occurred between sampling dates in Cantharis spp. and N. brevicollis larvae, respectively, suggesting that these predators utilized different feeding strategies. In both predator taxa, however, only few individuals (0·2–1%) tested positive for DNA of intraguild prey, indicating that predator–predator trophic interactions were scarce in this community.
4. Synthesis and applications. We present conclusive evidence that cold-adapted predatory beetle larvae are strongly linked to the detrital food chain by feeding on collembolans and earthworms. By improving the habitat conditions for detritivores in arable land by mulching, compost applications, or provision of plant cover during winter, their densities can be increased easily. Applying these measures year round will retain and sustain predatory beetles during their whole life cycle in arable land. Ultimately, we expect that these measures will enhance the ability of polyphagous beetle predators to provide their fundamental ecosystem service as regulators of agricultural pests.