How scientists are turning invasive crazy ants against themselves

Tawny crazy ants have been causing major problems in the southern U.S. for years. From Florida to Texas, these invasive pests have overrun yards, homes, and ecosystems.

The ants aren’t just annoying – they push out native species and throw entire environments out of balance. And once they move in, it isn’t easy to get them out.

But a team of scientists has figured out something that might finally work. It’s not a chemical spray or a trap. It’s a natural disease that spreads only among crazy ants – and only under the right conditions.

The crazy ants problem

Tawny crazy ants are not like the little black ants you see on your kitchen counter. They don’t follow normal colony rules.

Instead, they form what’s known as supercolonies. Ants from one nest in Louisiana will welcome ants from another nest in Florida as if they’re long-lost family.

This makes them much harder to control. You can’t just target one nest and expect the problem to go away.

The crazy ants are also aggressive. They edge out native ant species and even go after larger insects and small animals. Their numbers can climb into the millions in a single infestation.

A natural enemy

Back in the early 2010s, scientists in Florida discovered something strange. Some crazy ants were infected with a microscopic parasite called a microsporidian.

This pathogen only harms tawny crazy ants and leaves other insects alone. It hides inside the ants’ cells and spreads when adult ants care for their young.

That made it a great candidate for natural pest control. Infected ants could bring the disease into healthy colonies. If enough young ants caught it, the colony could collapse over time.

Cracking the ant code

In the lab, the idea worked. Infected ants easily passed the disease to new nests. But when scientists tried to do this in nature, it often failed.

The infected ants just weren’t getting close enough to the larvae – the young ants that needed to be exposed for the disease to spread.

The scientists realized that ant behavior was getting in the way. In nature, crazy ant nests are complicated. They have tunnels and chambers that keep different groups of ants separated.

Workers that take care of larvae stay near the center, while others handle trash or forage for food outside. This separation is smart. It protects the queen and the young from harmful things like mold, fungi – and in this case, disease.

Testing the social distancing theory

To test their theory, the team ran an experiment. When crazy ants were kept in a single-room box, infected ants reached the brood easily, and the disease spread.

But when the ants lived in multi-chambered nests, the disease was blocked. The infected ants couldn’t get to the larvae.

The research was led by Edward LeBrun, a scientist in the Department of Integrative Biology at UT Austin. It was a clear example of something called “architectural immunity.”

“This is the first demonstration that in ant societies nest spatial structure is of primary importance in allowing social immune behaviors to prevent diseases from reaching the colony core, where the queen and brood live,” said LeBrun.

Behavior under the microscope

The researchers noticed something else: infected ants acted differently. When placed near the queen, they didn’t stay there.

Instead, they moved to the outer edges of the nest and started doing jobs like removing dead ants or collecting food. They also avoided groups of other ants.

This behavior wasn’t random. It looked like self-isolation – almost like the ant version of quarantine. Healthy ants sometimes fought with the infected ones, as if they knew something was wrong.

Crazy ants protect each other

Infected ants even seemed to police themselves, cleaning up the bodies of other infected ants to protect the rest of the colony.

These types of behaviors had been seen before, but usually in response to mold or other external threats.

This study showed that crazy ants use them against internal infections, too – and that the behaviors work across different types of diseases.

Like humans, ants have systems in place to protect their communities during an outbreak. They separate the sick, avoid contact, and take extra steps to clean up infection sources.

Changing the strategy

Understanding how nest layout shapes ant behavior changed the team’s entire strategy.

Instead of gently adding infected ants to food trails or undisturbed nest chambers – a method that rarely let them reach the brood – the researchers now take the opposite approach.

“The way we do it now is we destroy the nest – we just tear it up – and then we introduce infected ants,” LeBrun said. “So then all the ants are mixed up and they’ve got to go move house and find a new environment.”

“And they all have to do that together, both infected and uninfected ants, and so it helps get past that period of both self-isolation and only doing tasks near where they were introduced.”

It’s a bit like forcing the ants into a group road trip. Everyone has to work together to rebuild, so the usual barriers break down. That gives the pathogen a real shot at spreading – and eventually bringing the colony to collapse.

“These results, and others not in the paper, have allowed us to reach the point where we can very reliably introduce this pathogen into uninfected local supercolonies in the field,” LeBrun said.

Crazy ants have met their match

This method isn’t just about dealing with one species of ant. It’s about understanding how animals organize themselves and use behavior to protect their communities.

The research shows how biology, observation, and persistence can solve problems that once seemed impossible.

And for homeowners and ecosystems along the Gulf Coast, it might just mean the beginning of the end for the tawny crazy ant takeover.

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