Winter is Coming For These Argentine Ant Invaders
Argentine ants are spreading across the globe, eliminating local ants with their take-no-prisoners tactics: invade, dismember, repeat. But this ruthless killer seems to have met its match in the winter ant, a California native with a formidable secret weapon.
– About Argentine Ants and Winter Ants
For about 200 years, the Argentine ant expansion story has been the slow-moving train wreck of myrmecology, the study of ants.
Wherever they go, Argentine ants eliminate the competition with a take-no-prisoners approach. Invade, dismember, consume. Repeat. The basic wisdom among ant scientists is that if you see Argentines, it’s already too late.
As early as the 1970s, scientists began to notice a peculiar fact about the Argentine ant. Usually, when ants from different colonies are put together, even from the same species, they fight. But Argentine worker ants can be combined from colonies in Spain, Japan and California, and they will recognize each other — they won’t fight.
Without this natural check, researchers say, a single colony of ants from Argentina has spread across continents and oceans.
But Jasper Ridge near Stanford is different. In 1993, ant biologist Deborah Gordon’s laboratory began tracking ant populations there. Jasper Ridge was unconquered territory for the Argentines, but they already had been spotted.
The Ph.D students conducting field research began to notice one species of native ant was holding its own inside the boundary of the Argentine advance. What, the Stanford researchers wondered, was different here?
In 2008, students in Gordon’s invasion ecology class studying the ants claimed to have made a novel discovery. The students watched the winter ants wave their abdomens at their enemies, known as “gaster-flagging” in ant circles, before a cloudy liquid blob appeared at the tip.
Approaching the secretion sent the Argentines reeling away. Touching it could kill them. Over the next two years, the students repeated and studied the winter ant’s apparently novel defensive behavior. They also analyzed the secretion. (Turns out it comes from the same gland used by the ants’ ancestors, wasps, to sting.)
They confirmed that in fact, with this amazing defense, the preserve’s winter ants were not only surviving, they’re now pushing back, opening up space for other native ant populations to rebound.
— Do Argentine ants bite?
Not people. Too small to hurt a human, they’re far more dangerous to their competitors, from other ants about their size to some small birds(!).
— How do you kill Argentine ants?
Pest control companies usually recommend slow-acting, fat or protein-based bait that allows the workers to carry the poison back to the nest.
— Why are winter ants called that?
In areas where temperatures dip below freezing, winter ants remain active while most ant species hibernate.
—+ Read the entire article on KQED Science: http://ww2.kqed.org/science/2016/05/03/winter-is-coming-for-the-argentine-ant-invaders/
—+ For more information:
Gordon Lab’s at Stanford University: http://web.stanford.edu/~dmgordon/
Neil Tsutsui Lab’s at Berkeley: https://ourenvironment.berkeley.edu/people/neil-tsutsui