In the insect world, impostors could be hiding anywhere.
When lifting a stone during an expedition in the Anti-Atlas Mountains in Morocco, researchers came across an unusual sight: three blowfly larvae living inside a termite nest.
“I immediately thought ‘Wow, this is something cool,’ because I’ve never seen anything like that,” says entomologist Roger Vila of the Institute of Evolutionary Biology in Barcelona.
Vila and colleagues brought the larvae and some termites to the lab, hoping to understand how the interlopers manage to get by unnoticed among harvester termites (Anacanthotermes ochraceus), which are known to kill intruders that enter their nests. The team examined the insects under the microscope, documented how the two species interacted and performed a number of experiments.
The blowfly larvae bodies have evolved to closely resemble those of the termites, the researchers report February 10 in Current Biology. Inside the nest, termites recognize each other through touch, so having a termite-shaped body is crucial for larvae survival.
On their rears, the larvae have features that resemble a termite’s antennae, eyes and other small structures, creating a false termite head. And tentacles around the body imitate termite antennae — allowing the larvae to deceive termites coming from all sides.
Scent also plays a role in the deception. In the dark underground, termites use chemical signals to recognize each other and each colony has a unique signature. “If you throw there a termite from another colony, they kill it immediately,” Vila says. The blowfly larvae, the researchers found, emit the exact scent that termites in the colony they exploit do.
It is unclear how blowfly larvae end up in the termite nest. The researchers speculate that adult blowflies lay their eggs around or inside of the nest, and that the termites “adopt” the impostors for unknown reasons. The larvae tend to stay in the most populated areas of the nest, the team says, so it’s possible that the termites might be feeding them.
The blowflies belong to the Rhyncomya genus, but the exact species remains a mystery. A second expedition unearthed just two more larvae and no adults, which would help ID the species. That suggests it is exceptionally rare.
Because other Rhyncomya species have larvae without mimicry, Vila says, “this tells us that evolution can be very fast under some circumstances.”
