Multi–predator effects produced by functionally distinct species vary with prey density
1Department of Entomology, Michigan State University, East Lansing, MI, USA
2Department of Entomology, University of Wisconsin, Madison, WI, USA
3Biology Department, Ursinus College, Collegeville, PA, USA
Abstract
Determining when multiple predator species provide better pest suppression than single species is a key step towards developing ecologically–informed biological control strategies. Theory and experiments predict that resource partitioning among functionally different predator species can strengthen prey suppression, because as a group they can access more prey types than functionally redundant predators. However, this prediction assumes that competition limits predation by functionally similar predators. Differences in prey density can alter the strength of competition, suggesting that prey abundance may modulate the effect of combining functionally diverse species. The experiment documented here examined the potential for functional differences among predator species to promote suppression of an insect pest, the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), at different prey densities. Predation was compared at two prey densities between microcosms that contained one predator species or two functionally distinct species: the lady beetle, Coleomegilla maculata De Geer (Coleoptera: Coccinellidae) that kills early L. decemlineata instars, and the soldier bug, Podisus maculiventris Say (Hemiptera: Pentatomidae) that kills late instars. The data show that combining these predators increased predation only when prey densities were low. This suggests that multiple predator species may only provide greater biological control than single species in systems where prey is limiting.
Keywords: biodiversity, biological control, Colorado potato beetle, functional diversity, Leptinotarsa decemlineata, natural enemy, resource partitioning
Abbreviations: ANOVA, analysis of variance; AP, Average proportion of L. decemlineata life stages predated, defined by Equation 1 in the text; PERMANOVA, permuted multivariate analysis of variance
Correspondence: a werlingb@msu.edu, b dmlowenstein@wisc.edu, c cstraub@ursinus.edu, d cgratton@wisc.edu, *Corresponding author
Received: 20 April 2011 | Accepted: 13 January 2012 | Published: 29 February 2012
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 12, Number 30
Werling BP, Lowenstein DM, Straub CS, Gratton C. 2012. Multi–predator effects produced by functionally distinct species vary with prey density. Journal of Insect Science 12:30 available online: insectscience.org/12.30
 Figure 1 |