Armies of “super ants,” which suffocate chickens and start fires by chewing wire, could be wiped out by a naturally occurring fungus, according to a study.
The tawny mad ant (Nylanderia fulva) is an invasive species that has been described as an “ecological wrecking ball” because it repels native insects and small animals.
Not only do they eliminate populations of other ants, experts say, but they can kill chickens by blocking their nasal cavities, causing them to die of asphyxiation.
Several yellow-brown mad ants also accumulate in electrical equipment, causing short circuits and clogging switching mechanisms, leading to equipment failures and fires.
Dubbed “crazy” for its rapid, unpredictable movements, the species is native to Argentina and Brazil, but has wreaked havoc during its spread across the United States over the past 20 years.
Now researchers in Texas have shown how to use a naturally occurring fungus called microsporidia to decimate local populations of crazed ants.
Microsporidian pathogens often hijack an insect’s fat cells and turn them into spore factories.
The tawny mad ant (Nylanderia fulva, pictured) is an invasive species that has been described as an ‘ecological wrecking ball’.
Several yellow-brown mad ants also accumulate in electrical equipment, causing short circuits and clogging switching mechanisms, leading to equipment failures and fires. Here tawny crazy ants swarm on a cobweb spider
THE BIZARRE TAWNY CRAZY ANT
The tawny mad ant (Nylanderia fulva) is a species of ant native to South America.
The species has quick, unpredictable movements and is reddish-brown in color. It’s about an eighth of an inch long.
The tawny mad ant differs from other commonly encountered ant species in that it lacks a stinging mechanism for protection.
So instead of stinging, the species gives off chemical compounds that protect it from attacks by other insects. While these ants can bite, they cause only mild pain that quickly subsides.
Multiple Tawny Crazy also accumulate in electrical equipment, causing short circuits and clogging switching mechanisms, leading to equipment failures and fires.
The bugs are strangely attracted to electrical wiring and components and caused $146.5 million in damage in Texas alone in one year, ABC reported.
The devastation occurs when an ant spots the transformer, then gets electrocuted when it touches it and “waves its belly in the air,” letting out a specific smell.
The scent attracts ants to the scene and they too are electrocuted, releasing the scent into the air again to lure their friends.
Eventually there are so many dead ants that the electrical switches get stuck or the insulation frys and the system shuts down.
First found in the US in Houston in 2002, scattered infestations are now found throughout the Gulf Coast counties.
According to the Brackenridge Field Laboratory, a single infestation can be huge, measuring several kilometers in diameter.
In Texas, it’s sometimes called the “crazy raspberry ant,” after exterminator Tom Rasberry, who noticed that ant numbers were increasing in 2002.
The study was led by Edward LeBrun, a biologist at the Brackenridge Field Laboratory in Austin, Texas.
In some parts of the state, homes were overrun by ants, which besieged circuit breakers, air conditioners, sewage pumps and other electrical equipment, causing short circuits.
‘I think, it [the fungus] has great potential for protecting sensitive habitats with endangered species or areas of high conservation value,” said LeBrun.
“It’s impossible to predict how long it will be before lightning strikes and the pathogen infects some crazy ant population.
“But it’s a great relief because it means these populations seem to have a lifespan.”
About eight years ago, LeBrun and Rob Plowes, also at the Brackenridge Field Laboratory, were studying mad ants collected in Florida when they noticed some had belly swollen with fat.
Looking inside her body, they found spores of a microsporidia, a group of fungal pathogens – a species new to science.
It’s not clear where the pathogen originated, although it may have originated in the native range of the tawny mad ants in South America, or from another insect.
LeBrun and his colleagues later found the pathogen in 15 local populations of mad ants across Texas.
Any population that had harbored the pathogen declined, and 62 percent of those populations disappeared entirely.
“You don’t expect a pathogen to cause a population to go extinct,” LeBrun said.
“An infected population typically goes through boom-and-bust cycles as the frequency of infections rises and falls.”
The ant colonies may have collapsed because the pathogen shortens the lifespan of worker ants, making it harder for a population to survive the winter.
Fortunately, the pathogen appears to leave native ants and other arthropods unharmed, making it a seemingly ideal tool for “biocontrol.”
The team deployed the pathogen this way after LeBrun received a call from Estero Llano Grande State Park in Weslaco, Texas, in 2016.
The park lost its insects, scorpions, snakes, lizards and birds to tawny crazy ants,” he said. “Rabbit babies were blinded in their nests by swarms of acid-spewing ants.
“They had a crazy plague of ants, and it was apocalyptic, streams of ants going up and down every tree.
Pictured: Microsporidia spores collected by Tawny, a mad ant, at Pace Bend Park in central Texas
“I wasn’t really ready to start this as an experimental process, but it’s like, OK, let’s just try it.”
Using mad ants they collected from other locations already infected with the microsporidian pathogen, the researchers placed infected ants in nest boxes near mad ant nest sites in the state park.
They placed hot dogs around the exit chambers to attract the local ants and merge the two populations.
In the first year, the disease spread to the entire mad ant population in Estero, Florida, and within two years their numbers were declining.
According to the researchers, the tawny crazed ants are no longer in the area, and native species are returning.
Edward LeBrun, a research associate with the Texas Invasive Species Research Program at the University of Texas at Austin’s Brackenridge Field Laboratory, collects tawny mad ants at a field site in central Texas
The team has since eradicated a second insane ant population at another site in the Convict Hill area of Austin.
They now plan to test their new biological control approach in other sensitive habitats infested with mad ants in Texas this spring.
Their study was published today in the journal Proceedings of the National Academy of Sciences.
GENETICALLY OPTIMIZED INDIAN JUMPING ANTS BECOME “SPACE CADETS”
In 2017, scientists genetically engineered ants to lack the sense of smell.
This hampered the insects’ ability to communicate, forage, or compete for a queen because their antennae and brain circuits could not fully develop.
Ants communicate through pheromones (chemicals that trigger reactions).
Such scents are used to spread alarm when a predator is approaching, leave a trail for food, indicate social status, and signal readiness for mating.
Ants can pick up such signals because they have proteins called olfactory receptors on their antennae, each protein being the right shape to bind to a specific olfactory chemical.
However, for an odor or pheromone to be processed in an ant’s brain, both the correct odorant receptor protein and a shared partner protein called orco must be present.
The team successfully engineered the genetic loss of the Orco protein, which resulted in ants being unable to perform some, if not all, pheromone-based social interactions.
In particular, the modified young ants spent much of their time migrating from the nest, in contrast to their unmodified nestmates. They were unable to interact with other members of the colony (a behavior referred to as “space cadet”) and were unable to forage and bring them back to the nest.
Also, mutant females no longer groom the males, a pre-mating behavior. The current study focused on the Indian jumping ant, Harpegnathos saltator, which is unlike many ant species where only the queen can mate and pass genes to the next generation.
Any female adult Harpegnathos worker can be transformed into a “queen-like” gamergate in the absence of the queen. This is because the queen secretes a pheromone that suppresses the workers’ ability to mate and lay eggs.
When the queen is removed, after winning a series of antennae duels, the most aggressive females go through this transition and can proceed to produce offspring, which is essential for colony survival.
The 2017 study found that without Orco, the females cannot process pheromones, making them much less likely to engage in duels.