Outcome of enemy-enemy interactions: role of behavior, life-history and scale

Abstract

Introduction: It has lately become evident that it is important to consider the combined, total effect of sets of natural enemies when evaluating the role of top-down forces in ecological systems. Methods: Field and laboratory studies were used to explore the outcome of enemy-enemy interactions on willows (Salix spp.). Two species of mirid bugs (Miridae) and an anthocorid bug (Anthocoridae) were studied. The two mirids are characterized by their habit of staying at a site and eat all prey before moving (‘find-and-stay’) whereas the anthocorid typically feeds on one or a few prey and then moves along (‘run-and-eat’). The bugs are all predators of leaf beetles (Chrysomelidae), an important pest in willow plantations used for producing biofuel. Results: At the scale of individual plantations, we found (1) a negative relationship between the density of two mirid bug species and (2) a tendency for a positive relationship between the density of the most common mirid bug and the anthocorid bug. At the scale of willow saplings, we found (a) an additive effect when combining two mirid bug individuals or when combining one mirid and one anthocorid bug, but (b) a negative, synergistic effect when combining two anthocorid bugs. Conclusions: Enemy-enemy interactions are likely to be negative when (a) enemies with active and similar behavior compete over prey or (b) enemies compete over a strongly limited resource. The interactions are neutral when (a) enemies with less active, but similar behavior compete over prey or (b) enemies with different behaviors compete over prey

Conference

XXIII INTERNATIONAL CONGRESS OF ENTOMOLOGY: ICE 2008

SLU Authors

• Björkman, Christer

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use
Agricultural Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/21236