Ant Wars

In this vast green earth, there’s an invicible war that is always raging, but went unnoticed.Why?

This is probably because the average militant is a mere 3 millimeters tall. In the largest war ever fought in the animal kingdom in the entire history of life on Earth, the Argentine ant species Linepithema humile has quickly and quietly taken over the entire world, wiping out all other ant species in its path.

Ants have a common militant nature, and they share a powerful instinct to protect their colony. There are essentially two types of ants in a colony: the queen and the worker ants. The queen’s sole function is to reproduce and maintain the population of worker ants. The worker ants are responsible for collecting food, growing the physical environment of the colony, and protecting the queen as well as their overall territory. The insect world is brutal; since rival populations can quickly smother each other, competition for space and resources is fierce. This competition has favored the evolution of very effective attack behaviors in ants. Any ant from a foreign colony, even if it is from the same species, will be immediately recognized as a foreign invader, and will be targeted for elimination.

L. humile, the Argentine ant, is especially adept at insect warfare. In its natural state, it is widely accepted as one of the more vicious and territorial insects. L. humile colonies within the natural range have genetic variations between populations that allows them to recognize each other’s colony of origin. This genetic distinction manifests itself as a distinct “smell” to the ants. In actuality, this smell is a combination of hydrocarbons unique to each colony. The ants use their antennae to examine the hydrocarbon structure on another ant’s exoskeleton, and they use that information to decide whether to attack or not.

In the 1800s, this recognition mechanism was fundamentally changed due to the trans-Atlantic trade. International traveling ants repopulated very quickly, establishing colonies in the Old World. After a few generations, the ants began behaving very strangely. In this new continent and unfamiliar environment, L. humile ants from different colonies did not attack one another; instead, upon coming into contact with L. humile ants from different colonies, they greeted each other like old friends. These colonies formed a kind of an alliance, and so multiple colonies with their own queens became a loose collection in a larger colony. This new cooperative social behavior began a territorial conquest that would make L. humile one of the most dominant species in the world.

As L. humile is one of the most skilled ant species in terms of militant behavior and colony attack tactics, it quickly swept through Europe and established a population that spanned the entire continent. As an invasive species with no established niche in the food chain, these ants had a powerful competitive advantage over other ant species. Their domination of Europe had a key consequence: Europe in the 1800s was a center of global trade. Ships were leaving for other parts of the world all the time, and just as it happened before, hitchhiking L. humile ants went along for the ride. The same pattern of colony establishment followed, and soon the Argentine ants took over large expanses of land all over the world. In every single one of these new territories, the species formed alliances within their own colonies. Today, we refer to these collections of ants as supercolonies.

Source :

Argentine Ant, 2014. (2014). Retrieved from https://cisr.ucr.edu/argentine_ant.html

Moffet, M. (2010). Adventure among ants. California: University of California Press.