Current address: CSIRO Entomology, Black Mountain, GPO Box 1700, Canberra, ACT 2601, Australia
Do differences in food web structure between organic and conventional farms affect the ecosystem service of pest control?
Article first published online: 8 JAN 2009
© 2008 Blackwell Publishing Ltd/CNRS
Volume 12, Issue 3, pages 229–238, March 2009
How to Cite
Macfadyen, S., Gibson, R., Polaszek, A., Morris, R. J., Craze, P. G., Planqué, R., Symondson, W. O.C. and Memmott, J. (2009), Do differences in food web structure between organic and conventional farms affect the ecosystem service of pest control?. Ecology Letters, 12: 229–238. doi: 10.1111/j.1461-0248.2008.01279.x
- Issue published online: 18 FEB 2009
- Article first published online: 8 JAN 2009
- Editor, Wim van der Putten Manuscript received 15 September 2008 First decision made 9 October 2008 Manuscript accepted 19 November 2008
- parasitoid diversity;
- species interactions
While many studies have demonstrated that organic farms support greater levels of biodiversity, it is not known whether this translates into better provision of ecosystem services. Here we use a food-web approach to analyse the community structure and function at the whole-farm scale. Quantitative food webs from 10 replicate pairs of organic and conventional farms showed that organic farms have significantly more species at three trophic levels (plant, herbivore and parasitoid) and significantly different network structure. Herbivores on organic farms were attacked by more parasitoid species on organic farms than on conventional farms. However, differences in network structure did not translate into differences in robustness to simulated species loss and we found no difference in percentage parasitism (natural pest control) across a variety of host species. Furthermore, a manipulative field experiment demonstrated that the higher species richness of parasitoids on the organic farms did not increase mortality of a novel herbivore used to bioassay ecosystem service. The explanation for these differences is likely to include inherent differences in management strategies and landscape structure between the two farming systems.