Franchising ants

TLDR : Argentine ants are a big bunch of bastards. But do read it, because they're fascinating bastards.


To protect territory, Argentine ants will attack other ants, but mostly they starve out other species by consuming resources. Wild summed up their strategy by comparing them to Walmart:

Their colonies are connected over a vast scale, so individual nests can operate for a long time at a loss until they drive competitors out of business. In California, the native ant colonies are local and smaller. Argentine ants are in these sprawling colonies that can import resources from somewhere else. They can operate satellite nests at a loss like these big franchises.

Argentine ants wreck natural ecosystems by pushing out the local ants. University of Illinois at Urbana-Champaign entomologist Andy Suarez told Ars that native ants provide valuable services to the environment, and when Argentine ants push them out, the effects are felt across several species.

For example, California harvester ants bury seeds deep in the ground and aerate the soil, which is good for trees. But when Argentine ants drive out harvester ants, the soil is less absorbent and trees don't get as much water. Additionally, coastal horned lizards have a lot of harvester ants in their diets. Without harvester ants, these lizards may die back or worse. "Displacement of native species results in cascades in the ecosystem," Suarez explained. Ultimately Argentine ants aren't just killing other ants—they're harming trees and lizards, too. The loss of those trees and lizards will affect other species, and so on, until you're looking at potentially dozens of extinctions caused by one very persistent group of pests."

But spring isn't just about expansion. For Argentine ants, it's also time for their annual sacrifice. Hidden from human eyes, in shallow tunnels beneath tree trunks and underground, the worker ants kill 90 percent of their queens. By one estimate, the queens go from 30 percent of the population to less than five percent. It's hard to say why the workers would do this at the beginning of their mating season; Tsutsui called it "mysterious and bizarre behavior." So far, scientists have not been able to figure out whether this annual sacrifice changes the genetic makeup of the colony. It seems that the queens are killed with little regard for age, fitness, or genetic relatedness to the rest of their sisters.
http://arstechnica.com/science/2016/08/meet-the-worst-ants-in-the-world/