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Hybrid imported fire ants (S. invicta x S. richteri) outcompeted several native ant genera at baits in pasture and field sites in southeastern Tennessee. They more quickly discovered and recruited to baits than native ants, and they ultimately controlled more baits. After half of the fire ant mounds were experimentally removed by poisoning, native ants were quicker than fire ants to discover and recruit to baits, but fire ants still ultimately controlled about half the baits. Interactions between fire ants and native ants at baits were very rarely directly aggressive; rather, either the later arrival left or the different species spatially partitioned the bait without fighting. Occasionally control of a bait changed between species, but such shifts were not accompanied by aggression between the contenders. These results suggest that, like the red imported fire ant, Solenopsis invicta, the hybrid fire ant outcompetes native ants in disturbed habitats. This competitive superiority rests at least partly on numbers, and interference competition is not operating at the scale of individual baits. [ABSTRACT FROM AUTHOR]

The article presents a rejoinder to the paper "Invasional Meltdown 6 Years Later: Important Phenomenon, Unfortunate Metaphor or Both?" by Daniel Simberloff of the Department of Ecology and Evolutionary Biology in the University of Tennessee in Knoxville, Tennessee. The author stated that he was unconvinced that searching for positive feedbacks would better serve the progress on evaluating invasional meltdown than studying population and community-level consequences of identified interactions. He added that it still remains to be confirmed whether population impacts of facilitation actually contribute to meltdown.