Just when you thought insects just couldn’t get any wackier, along comes…

Kamikaze Ants!!

(The south-east Asian Camponotus cylindricus)

Johan Billen of the Catholic University of Leuven (KUL), Belgium and his team researched a kind of ant that’s especially evolved to kill itself in order to save the nest.

Several south-east Asian species of ant in the Camponotus cylindricus group (i.e. carpenter ants) have enlarged mandibular glands that extend into their gaster (the bulbous posterior portion found in bees, wasps and ants). When disturbed, the ants rupture the membrane of the gaster, causing a burst of secretions containing chemicals – the largest gland reservoirs yet known in ants – that immobilize small insect attackers and kills the ant.

Or, as the folks at Newscientist.com put it, “The ants of Borneo go out with a bang, thanks to a body built to blow up during a suicidal death grip.”

In other words, the six-legged blast-ended ant grabs onto the invading enemy and squeezes itself to death, literally blowing itself up and shpritzing a deadly sticky yellow goo everywhere, killing both intruder and ant.

And these little suicide bombers operate on a hair-trigger; their abdomen walls ruptured even when researchers lightly touched them!

Now while all 10,000 species of ant have glands in their jaws to release chemicals in alarm or defence, in at least nine species of the Cylindricus complex of ants most of the body is given over to storing the deadly secretion… to the point that they have very little space in their bodies for food. That’s one heck of a payload!

(Ant anatomy)

And it’s not like the little buggers only blow themselves and their enemies close to home. Kamikaze ants have been known to carry a suicide explosion mission onto enemies far from the colony.

The exploding ants were first reported by a German biologist in the 70’s. He noted that when he grabbed the ants with forceps, they would explode. He even took them back to Europe and introduced them to other ants and the result was the same… the ant would clasp on to the other ants and explode.

Diana “Dinah” Davidson, one of the study’s authors and a retired ecologist from the University of Utah, was so fascinated by the ants that she paid her own way to Brundei on the island of Borneo to study the ants in the field.

What Davidson and her team found was the reason for what the suicide bomber ants did what they did. Davidson clarified that what’s odd about this finding is that these ants are not directly protecting a nest, but they are protecting a foraging territory that can be “hundreds of meters from the nest.”

“Organisms don’t usually commit suicide,” she said. Of course there are other examples, some termites and honey bees commit suicide, but Davidson explains, it’s to protect a queen, which is the “reproductive individual.”

“If you’re going to find suicide it’s not surprising to find it in social insects. It was surprising to find it so far from the colony,” said Davidson.

(Carpenter ant)

While all ants will fight to the death to protect their nest, Davidson said this is different. “Not all ants will blow themselves up,” she said. And the way they do it means it’s “intentional self-sacrifice, voluntary self-sacrifice.”

Sounds like some kind of bug bushido samurai philosophy at work here.

If that isn’t cool enough, they way these self-exploding ants do it is delightfully gross!

“They grab the leg and wrap themselves around the ventral side of that opponent and when they do that the mandibular gland compound comes out through the anterior mandibular gland opening and they are forced out through pressure because the ant is squeezing itself,” said Davidson.

That’s right: The ant squeezes itself to death.

“They burst through the intersegmental membrane of the ant’s abdomen… killing the ants,” said Davidson. The ants end up “permanently glued to the opponent because the compounds are very sticky and they tumble from the canopy as a pair into the leaf litter and are eventually eaten by something.”

Quite a gift for imagery, our Ms Davidson has! Well done.

Well, folks… that’s it until next time something catches my attention from the ever-bizarre world of nature!