Hundreds of ant species have been moved by humans
across biogeographic barriers since continental explorations
began (McGlynn 1999). Some species, including
the red imported fire ant (Solenopsis invicta), have established
on most continents, where they have large ecological,
economic, and social consequences (Holway et al.
2002). Ecological analyses of ant invasions typically focus
on disruption of native ants and other invertebrates
(e.g., Rowles & O’Dowd 2007; Bos et al. 2008), but
some evidence shows that plants and vertebrates are adversely
affected (e.g., Suarez et al. 2000; Christian 2001).
For example, by disrupting native ant communities in
California, Argentine ants (Linepithema humile) reduce
prey availability for the horned lizard (Phrynosoma coronatum)
(Suarez et al. 2000). Mutualisms between invasive
ants and honeydew-secreting Hemiptera (Styrsky &
Eubanks 2007) may further amplify and diversify impacts
on vertebrates. Red imported fire ants derive nearly half
of their energy supply from honeydew (Helms & Vinson
2002), and this resource may fuel forager activity sufficient
to disrupt ground-nesting birds (Allen et al. 2004).