locations, but fire ant recruitment decreased in both control and crazy ant addition
locations, suggesting that crazy ants responded to, rather than caused, drops in fire ant
recruitment. Together, these findings suggest that crazy ants may not be able to displace
fire ants in areas that cannot support high crazy ant densities, a factor which may restrict
the potential spread of crazy ant populations and enable the two invasive species to
coexist in a patchy distribution.
Introduction
Colony-level antagonistic interactions are fundamental to the structuring of ant
communities (Holldobler and Wilson 1990). Though aggression assays which focus on
worker interactions usually accurately predict whether two colonies will behave
aggressively towards one another (Roulston et al. 2003), they do not necessarily predict
which colony will have a competitive advantage. In some species, such as the highly
invasive Argentine ant (Linepithema humile), an individual ant may not be successful in
one-on-one interactions with their competitors, but as part of a larger colony, the ants can
Outcompete and displace competing colonies (Holway 1999, Buczkowski and Bennett
2008). In this study, a laboratory and a field experiment were used to assess the colony-
level competitive ability of the non-native Rasberry crazy ant, Paratrechina sp. nr.
pubens. In the lab, Rasberry crazy ants were paired with red imported fire ants,
Solenopsis invicta, while crazy ant colonies in the field interacted with the existing ant
community in the coastal tailgrass prairie of the Texas Gulf Coast, a habitat which is
dominated by fire ants. This is the first time that colony-level competitive ability has
been assessed in the recently introduced invasive threat, Rasberry crazy ants, and it is the
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