Red Fire Ants

Biotic invasions can predominantly alter the dynamics, composition, functions, and structure of natural ecosystems. Social insects, particularly ants, are among the most damaging invasive alien species. Invasive ant species are among the supreme threats to ecosystems. There are about 23 species of invasive ants recorded worldwide, according to the ant invasive databases. The ecological impacts of invasive ants comprise predation, hybridization, and competition with native species that changes the ecosystem processes with the biodiversity loss and upsurge of pests. The effects of invasion on native fauna in the same habitats might be catastrophic for the native community through various ecological mechanisms, e.g., habitat disturbance, resource competition, limiting the foraging activity of native species, and various other indirect mechanisms of invasive species. Invasive species may have harmful impacts on habitats and devastating effects on natural flora and fauna, and stopping these new species from being introduced is the most effective way to deter future invasions and maintain biodiversity. This paper reviews the literature to evaluate the effects of invasive ant species on the native species, including vertebrates, invertebrates, and plants sharing the same habitats as the non-native species under global environmental changes. We also highlighted the various management strategies that could be adopted in minimizing the adverse effects of these invasive ant species on the natural ecosystem. To this end, strategies that could regulate the mode and rate of invasion by these alien ant species are the most effective ways to deter future invasions and maintain biodiversity.

Unicoloniality, or the absence of behavioral boundaries between nests, is thought to promote ant abundance due to reduced intraspecific competition. Workers within unicolonial populations may increase their own inclusive fitness by preferentially caring for more related individuals (nepotism), but nepotism has only rarely been documented in ants. We tested for unicoloniality and nepotism in polygyne red imported fire ants (Solenopsis invicta; hereafter fire ants). Fire ants occur in two social forms: monogyne (i.e., colonies with a single egg-laying queen) and polygyne (i.e., colonies with multiple egg-laying queens). Introduced populations of polygyne fire ants are commonly referred to as unicolonial, but cooperation between and within colonies is poorly documented. To delimit boundaries between colonies in the field, we quantified the exchange of a 15 N-glycine tracer dissolved in a sucrose solution and correlated this exchange with colony genetic structure. We also quantified within-colony conflict between workers and larvae using close siblings (i.e., from the same mother) and non-siblings (i.e., from a different mother). Counter to our expectations, polygyne colonies did not exchange resources or workers, indicating distinct colony boundaries. Polygyne workers also preferentially fed larval sibling and may have preferentially cannibalized non-siblings. Polygyne colony behavior was correlated with higher levels of within-mound relatedness between workers in the field than those previously reported in North America (mean ± SE: 0.269 ± 0.037). Our study challenges fundamental assumptions about introduced populations of polygyne fire ants and suggests that polygyne colonies are multicolonial and likely engage in high levels of intraspecific competition.

Fire ants are widely studied, invasive and venomous arthropod pests. There is significant biomedical
interest in immunotherapy against fire ant stings. However, mainly due to practical reasons, the
physiological effects of envenomation has remained poorly characterized. The present study takes
advantage of a recently-described venom protein extract to delineate the immunological pathways
underlying the allergic reaction to fire ant venom toxins. Mice were injected with controlled doses of venom protein extract. Following sensitization and a second exposure, a marked footpad swelling was observed. Based on eosinophil recruitment and production of Th2 cytokines, we hereby establish that fire ant proteins per se can lead to an allergic response, which casts a new light into the mechanism of action of these toxins.