Fire ants – queens, clones, and burning bites


The 5th of November is upon us, the day Guy Fawkes decided to blow up Parliament (and failed). With bonfires and fireworks lighting up throughout the UK, we thought we’d highlight some fiery research. Don’t worry, we won’t be discussing the adverse health risks of fumes or  the danger of wildfires. Instead we’ll be looking at the fire ant in all its blazing glory.

The fire ant is just a name for ants of the Solenopsis genus. You may also know them as the ‘red ant’. There are about 285 species of fire ant worldwide.

Flame fatales

The ladies are, like most female ants, born into royalty as a queen. As a virgin, the queen is equipped with a set of wings. Mating is done mid-air and ends with the queen killing her male and landing. After this, she rips off her wings, and eats them for sustenance; they’re no longer in fashion or of any use to her.

Distribution of sNPF receptors in the red ant queen’s posterior brain

Looking inside the brain of a queen yields interesting results. In a study published in BMC Neuroscience, researchers looked at a particular receptor in the brain. The short neuropeptide F receptor, also known as sNPF, has been suggested to be involved in food regulation, food intake, and thus weight gain. In other words, insects with more of these receptors tend to eat more, and get bigger. When insects go dormant, sNPF receptors may also affect feeding behaviour, causing them to eat plenty beforehand, retaining the appropriate body size during inactivity. These receptors were found all over the queen – from ovaries to antenna – preparing her for reproduction and helping her maintain her large body size compared to her male minions.

Bites that burn

Insect bites can be dangerous to humans if they happen to be allergic. In a recent case of fire ant biting, a woman in Canada fell victim to anaphylaxis, which took her a few days to recover from. This was the first case of anaphylaxis caused by fire ants in Canada. They are known to be invasive, and this seems to be yet another country infiltrated. How they succeeded remains a mystery to the researchers, who are urging physicians in Canada to prepare for further cases similar to this one.

Attack of the clones

Detailed genetic analyses of the little fire ant, or electric ant, Wasmannia auropunctata, revealed an unusual mode of reproduction used by males.  The findings in Nature from 2005 revealed that these little fire ant males were all genetically identical. It seemed that the male electric ants most likely reproduce clonally, which was the first evidence of male asexuality in ant colonies.

Female queens also produce clones , denying males the opportunity to pass on their genes. Perhaps this is for the best – sexual reproduction means inevitable death for males. Eventually it seems these two sexes have almost diverged into separate species, with males and females fending for themselves, yet relying on one another. Females need the males as workers, males need the females for their eggs.

These products of cloning are renowned pests, and it’s not uncommon to find explosions of these populations after environmental stresses. Don’t be fooled by their size, these insects can have a damaging impact on biodiversity. They are known to not only to harm other insect and arachnid species, but even turtle hatchlings.

To find out more about these fiery clones, take a look at this great overview of the research in our Genome Biology journal.

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