Journal
ECOLOGY
Volume 90, Issue 5, Pages 1184-1194Publisher
WILEY
DOI: 10.1890/08-0852.1
Keywords
biological control; central Texas, USA; competition; competitive displacement; fire ant control; phorid fly parasitoid; Pseudacteon curvatus; Pseudacteon tricuspis; rare species; Solenopsis invicta; trait-mediated indirect effect
Categories
Funding
- State of Texas Fire Ant Initiative (FARMAAC)
- C. Kleberg and Robert J. Kleberg Foundation
- Lee and Ramona Bass Foundation
Ask authors/readers for more resources
Species abundances in natural systems are usually close to some equilibrium, making mechanisms that maintain or prevent species coexistence difficult to discern. Biological control projects provide an opportunity to observe systems transition between equilibriums as a result of the influence of the newly introduced species. In the southeastern United States and Texas, species of phorid fly parasitoids are being sequentially introduced as control agents for imported fire ants. The first two species introduced, Pseudacteon tricuspis and P. curvatus, partition the host niche based upon body size and co-exist broadly in their native range in Argentina, indicating they would form a co-existing and complementary suite of parasitoids in North America. This study examines the interaction between these parasitoids at multiple temporal and spatial scales. Surprisingly, data at all scales reveal that as P. curvatus establishes at a site it competitively displaces P. tricuspis. However, the speed of this reduction appears to differ between ecoregions, suggesting that the rate of displacement depends on environment. At the site where P. curvatus has been established the longest, this population interaction approaches complete displacement. Tests of potential mechanisms causing this displacement reveal that direct competition for host workers alters the operational sex ratio of the P. tricuspis population, but the strength of this effect is insufficient to explain the displacement. Experiments reveal the operation of a strong, indirect effect whereby locally common species preempt reproductive opportunities from rarer species by inducing host behavioral defenses. Finally, a re-examination of published data from their native range reveals that a previously overlooked negative relationship between the densities of these two species also exists there, suggesting that the same processes as those reported here also operate in South America.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available