Solenopsis invicta, more commonly known as the Red Imported Fire Ant or RIFA, is one of the most successful invasive species on the planet. Therefore, they must be very quick and efficient at reproduction (Taber 2000).  The mating of these ants is a unique process, and usually occurs between spring and fall. However, they have been known to mate in the winter in places where climates are warm (Taber 2000).  Winged males and winged females, called alates, engage in a mating ritual while in flight (Smithsonian Marine Station 2007).  Amazingly, some of these mating individuals have been captured at heights approaching 1000 feet in the air (Taber 2000).  The male dies shortly after the mating process concludes.  Females remove their wings after the mating ritual as well, so they can enRIFA nest in grass courtesy of Queensland Government and SARE and Texas A & M Universitycompass their reproductive roles more entirely (Klotz et al. 2008). The female, or queen, then finds a suitable location to begin a colony (Smithsonian Marine Station 2007).  She will then dig chambers into the ground, where she will lay her initial batch of eggs (Entomology and Plant Pathology 2013).
    Once eggs are laid by the queen, she covers them with antibiotic venom to protect the offspring, which may also be used as a signal for workers to carry them away to a different part of the nest.  However, the first batch of eggs is raised in a way that differs from the future generations to come.  These eggs are nourished by the queen herself via nutritious trophic eggs, oil she has regurgitated, or her own saliva (Smithsonian Marine Station 2007).  These first eggs are hatched, but are smaller than future generations due to the fact that the queen has to feed them herself.  These first female workers then develop and take charge of feeding future offspring of the queen (Smithsonian Marine Station 2007).
    Ants develop in stages, starting as eggs and further developing to larvae, pupae, and finally adult form (Klotz et al. 2008).  A unique feature to S. invicta colonies is that the queens can produce diploid males, unlike many other ant species (Taber 2000). However, a feature of all ants is that they are eusocial insects, which influences their success.  They exhibit cooperative care of the young, labor division, and an overlapping of generations in their colonies.  A mature colony, which reaches this point three years after initial copulation, may comprise of anywhere between 100,000 and 500,000 workers, and hundreds of alates (Entomology aFire ant life cycle courtesy of the State of Queensland, Department of Agriculture, Fisheries and Forestry, 2010-2013 Plant Pathology 2013).  S. invicta queens can live to be up to seven years old, which helps attribute to how successful colonies are at reproduction (Taber 2000).
    A unique occurrence in the species S. invicta is that it has evolved both social forms that are found in ant colonies. One type of colony is the multi-queen polygene form, which has many queens that are not territorial (Klotz et al. 2008). There can be thousands of queens in this form of colony, some which are mated and some which are not. Polygene colonies can grow to be so large that they can have numerous mounds per colony (Taber 2000). This form of colony is thought to be more successful in respects to density of population than the second type, the monogyne colony. This other type of colony is singular and territorial, with one queen. This form of colony has subsequently low population densities (Klotz et al. 2008).  Infiltrations by monogyne nests are also less numerous and calamitous than the polygene type (Allen et al. 2004). However, monogyne queens each lay far more eggs than their polygene counterparts, and their workers are larger in size (Taber 2000).
    No matter what form of colony that S. invicta displays, one thing is certain.  The reproductive success of this invasive species is very impressive, especially in the places all around the globe to which they have spread besides their native lands of South America.  This copious invasive species has major impacts and interactions with many different organisms. Click here to learn more about the interactions of S. invicta.


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