have since spread throughout more than 106 million hectares of the southeastern US, the
Midwest, and California, where they are the dominant ant species in disturbed habitats
(Williams 1994). Due to their harmful effects on humans, agriculture, and ecosystems,
fire ants cost nearly $1 billion per year in economic losses and control efforts (Pimentel
et al. 2000). Some news reports have suggested that crazy ants attack, eat, and displace
fire ants, yet none of these claims have been tested. Due to the widespread invasion of
fire ants and the locally abundant populations OfRasberry crazy ants, interactions
between these two species may be very important in affecting the spread of crazy ant
populations.
To examine the intra- and interspecific interactions of the Rasberry crazy ants, the
following sets of ant pairings were observed: 1) crazy ants and either small (minor) or
large (major) fire ants workers, 2) crazy ants from nests in the same supercolony which
had been isolated and fed one of two protein sources and either high or low doses of
sugar water, and 3) crazy ants which had been on the different diets described above and
fire ants. Two sizes of fire ants were used because both minor and major fire ants forage
outside of the nest where they can interact with crazy ant foragers, and the different sizes
of fire ants could have different fighting tactics or abilities which may affect their
likelihood to engage in fights and/or their ability to kill ant opponents. All interactions
were examined using aggression assays with 5 ants from each species or treatment in a
Petri dish, which have been shown to be highly consistent and correlate well with full
colony introductions (Roulston et al. 2003). Together, these three sets of aggression
assays made it possible to address the following questions: 1) Are crazy ants or fire ants
more successful in fights? 2) Is fighting success affected by fire ant size? 3) Do
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