For those of us in the northern hemisphere the days are shorter and colder. That can only mean 1 thing: Winter. Countless animal species will begin hibernating if they haven’t already. Ants are no exception, with countless colonies and species hunkering down for the winter. As you can probably guess from the title and the fact that I am even talking about ants in the winter, there is an exception. Deception and suspense don’t really work if you’ve already read the title.
The ants I am talking about, Prenolepis imparis, are known as winter ants or false honeypot ants. They are called this because, much like the ‘true’ Honeypot ants, they use their bodies to store food. They do not, however, permanently change their morphology to achieve this, making them ‘false.’ To find out more about this and honeypot ants in general, you can do so here.
This article will focus more on their behaviours that earn the title of ‘winter ants.’ While most species in these northern regions will be hibernating, these ants will be waking up.
Most ants avoid the cold weather because they are Ectotherms meaning they get a lot of their body heat from their environment. Cold temperatures mean they will have less energy and will slow down until they die. Very cheerful! So, where it is needed, ants hibernate. Not these girls!
The reason they do this is to avoid competition. During the warmer months, they would need to compete with all other species present for resources while also needing to defend themselves from predators. Very risky. Of course, being active in colder months comes with its own risks (see freezing to death), but the reduced presence of predators and competition for food are worth the risk.
While they are adapted to foraging in literally freezing conditions, they struggle in the heat so they undergo what is called aestivation. This is essentially hibernation during the warmer parts of the year. Their range, however, makes this difficult as they are found as far south as Veracruz in Mexico, not a very cold place. They combat this with their nests.
This species creates exceptionally deep nests that stretch over 3.6 metres into the ground. Very deep for an ant whose workers are around 4mm long. This deep, the nest will maintain a steady, low temperature as the heat from the sun doesn’t really penetrate this far down. Especially as they seal up the nest entrances. This way they are able to remain in a state of relative dormancy, using their repletes to survive.
This strategy works. They wouldn’t have evolved it if it didn’t. It also has another great affect on their survival. They are hidden when invasive ant species, notably Linepithema humile, are active. This means they are very resistant to the negative effects this species has on other native species. They are also well suited to defending against this threat as they secrete a substance which is lethal to Linepithema humile.
So that is how this ant thrives. The moral of this story is that sleeping is a valid way of avoiding your problems doing things differently doesn’t mean you are doing them wrong. Thanks,
Alex.
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References
AntMaps
AntWeb
Hölldobler, B. and Wilson, E.O., 1990. The ants. Harvard University Press.
Sorrells, T.R., Kuritzky, L.Y., Kauhanen, P.G., Fitzgerald, K., Sturgis, S.J., Chen, J., Dijamco, C.A., Basurto, K.N. and Gordon, D.M., 2011. Chemical defense by the native winter ant (Prenolepis imparis) against the invasive Argentine ant (Linepithema humile). PLoS One, 6(4), p.e18717.
Tschinkel, W.R., 1987. Seasonal life history and nest architecture of a winter-active ant, Prenolepis imparis. Insectes Sociaux, 34(3), pp.143-164.
Wheeler, W.M., 1930. The ant Prenolepis imparis say. Annals of the Entomological Society of America, 23(1), pp.1-26.
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