New Brunswick

'Extremely rare' slave-making ants found at Kennedy Lakes

Entomologists are thrilled by the discovery of a new genus of ants in Atlantic Canada.

BiotaNB 2019 sees thousands of life forms collected in remote protected natural area

The rare ant Harpagoxenus canadensis enslaves Leptothorax canadensis worker ants. Six colonies of them were found in slightly rotting birch branches at the Kennedy Lakes Protected Natural Area. (Aaron Fairweather/Twitter)

There's something sinister going on in the Kennedy Lakes Protected Natural Area, about halfway between Renous and Plaster Rock.

"We're talking murder, kidnapping, enslavement — all of this going along the side of the highway as we're driving by," said Donald McAlpine, curator of zoology at the New Brunswick Museum.

Insect specialists taking inventory of the protected area last week as part of BiotaNB discovered an "extremely rare" type of ant that parasitizes another ant species.

"We were kind of shocked at first," said Aaron Fairweather, a doctoral candidate at the University of Guelph, describing the moment when two types of ants — one a bit larger than the other — were found living together in a rotting birch branch.

"We were like, 'What's going on here?' We never really see this."

Rather than surviving on their own and trying to forage for themselves they need to invade a colony and make their workers do their dirty work.- Aaron Fairweather

Back at the field laboratory, a review of the scientific literature pointed to Harpagoxenus canadensis, a type of ant that has only been found in a handful of places worldwide.

"When a Harpagoxenus canadensis queen flies out and tries to establish a colony, it first tries to find this Leptothorax canadensis colony," explained Fairweather.

The queen invades the other colony, kills its queen and makes its workers tend to her eggs and her colony.

As the colony grows up, the Harpagoxenus canadensis workers start to "maraud" around.

"They leave the colony … find another colony of Leptothorax canadensis … kidnap the breed and bring them back to the nest and raise them as their own."

It may sound evil to humans, said Fairweather, but "nature is scary."

There are a few species of ants known to do this.

Buck Trible, left, and Aaron Fairweather collect insects during BiotaNB 2019 at the protected natural area. (New Brunswick Museum/Facebook)

"It's a trait that has converged several times in the ant group over millions of years, but it's an amazing strategy. Rather than surviving on their own and trying to forage for themselves they need to invade a colony and make their workers do their dirty work, pretty much."

This species was found in Quebec before, but it's never been known to live in Atlantic Canada.

There are likely small dispersed colonies wherever Leptothorax canadensis is, said Fairweather, and a queen can fly for kilometres to find a nest site. But those habitats require very specific conditions and are few and far between.

"It's so exciting," said Fairweather.

"We found it six times in that location, which means the density is pretty high compared to anywhere else it's been found before. And that is very special."

Entomologist Tony Thomas says what makes the rare ant find even more remarkable is its small size. These are two ants Thomas collected at Kennedy Lakes. The small one is similar in size to Harpagoxenus canadensis, five to six millimetres long. The larger is a queen carpenter ant. (Submitted by Tony Thomas)

Fairweather said he plans to return next summer to do more intensive sampling and try to home in on why the slave-making ant seems to be doing so well at Kennedy Lakes.

It's a species that can be used as an indication of forest health, he said.

"If a forest is healthy enough to support a high density of the host species, the slave-making ant will come along. That just speaks about the habitat, that it's able to keep the species sustainable."

When they happened upon the strange colony, Fairweather was helping Buck Trible, a post-doctoral researcher from Harvard University, look for "enigmatic" leptothoracine ants.

"These ants can be studied both in the wild and in the laboratory and are helping us to understand how animals evolve in different ecological conditions," said Trible.

Entomologists found 25 workers of Harpagoxenus canadensis and 39 workers of the slave Leptothorax canadensis in one of the colonies at Kennedy Lakes. (Aaron Fairweather/Twitter)

The parasite ant exploits the Leptothorax canadensis ant's social structure, he said.

Because of the rarity of Harpagoxenus canadensis, very little research has been done on it since the 1980s.

The parasite ants at Kennedy Lakes could be a "potential study population to better understand its biology," he said.

Trible considers the protected natural area "an important refuge" for these ants.

Fairweather has been taking part in BiotaNB for 11 years now and has identified 86 different species of ants living in New Brunswick protected natural areas.

This year, thousands of specimens of flora, fauna and fungi were collected during the Biota event, said McAlpine.

They include moths, deer flies, earthworms, small mammals, vascular plants, trees, shrubs, wildflowers, lichens and mosses.

Amphibian researcher Greg Jongsma of the University of Florida holds an American toad, a common species in eastern North America. The toads are not frost-tolerant, the way many other amphibian species in the province are. They dig nearly two metres down in the dirt with their hind legs to hibernate. (New Brunswick Museum/Facebook)

Fairweather and Trible were able to identify the parasite ant quickly, but typically it takes a lot more study, up to a genetic sequencing to figure out exactly what's been found during a so-called bio-blitz.

For example, a paper coming out next month describes a new species of flower fly, or syrphid fly, that was collected in 2015, McAlpine said. The Biota event that year was in the Nepisiguit Protected Natural Area.

"So it will be a while before we know exactly what we've got, but we know we've got some pretty neat stuff," said McAlpine.

Greg Jongsma was the visiting amphibian expert at the Kennedy Lakes Biota.

"As museum scientists, we will often never see the fruits of our labour, but take solace knowing we have provided the raw materials that future generations of scientists can use to explore the past."

Jongsma said much of his work today uses modern technologies to unlock data from museum specimens in ways the original collectors could never have fathomed, such as extracted DNA from frogs and the diseases that infected them.

"Some of these diseases are causing rampant extinctions today so understanding their historical spread around the world is critical for controlling diseases like chytridiomycosis," he said.

The fungus that causes that disease has been detected in New Brunswick, Jongsma said, and he and others are working to monitor its impact at places such as Kennedy Lakes.

"It is exciting to report that the frog populations appear to be doing well across this PNA and there are no apparent population declines."

With files from Shift and Information Morning Saint John