isolation. Fire ant worker size had little effect on antagonistic interactions with crazy
ants, as aggression score, the number of crazy ants fighting, and mortality for both
species were not influenced by fire ant size. The exception is that small fire ants fought
more than 50% more often than large fire ants (Figure 2.1). The tendency of small fire
ant workers to fight more often may be biologically important, as small fire ants are
nearly 3 times more common than large fire ants based on the average distribution of
worker sizes in our field-collected colonies (Table 2.1). This may mean that crazy ants
are more likely to encounter small workers that readily engage in fights than large
workers that avoid fights, especially since smaller fire ant workers have been found ot
forage farther from nests (Martin and Vinson 2008). The increase in fire ant fighting
does not correlate with an increase in mortality for either crazy ants or fire ants,
suggesting that the likelihood of engaging in fights may not be indicative of the outcome
of interactions. Overall, crazy ants, which spray formic acid with an acidopore, had an
average mortality nearly twice that of fire ants (Figure 2.3), which inject acid using a
stinger (Holldobler and Wilson 1990). This large average difference was not statistically
significant perhaps due to the small sample size and the low power of a non-parametric
test, and it is possible that the difference in mortality between the two species is
biologically significant. Though spraying acid can be a very effective method of
attacking other insects, as the acid is absorbed through the exoskeleton, crazy ants may
have less success in fights with fire ants due to the difference in size, as even small fire
ant workers are significantly larger than crazy ants. If the advantage of fire ants over
crazy ants in individual clashes is biologically significant, it could be important in
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