Tropical Wasp Guards Nest Using Facial Recognition

If you're a member of a wasp species in the tropical forests of Southeast Asia, you'd better hope your colony-mates can recognize you on sight, or you risk being punched in the mouth.

That's what scientists from Queen Mary, University of London (QMUL) found when they took a look at how the wasp species Liostenogaster flavolineata weighs facial recognition vs. odor cues when trying to tell friend from foe.

It's not uncommon for the wasp to need to figure that out. Hundreds of its nests, each housing families of related wasps, can be clustered together, in what can look like a wasp city (see photo below). Intruders, bent on taking resources, show up often.

Most insects know how to identify fellow colony members by a scent that's specific to that colony. But the new study documents wasps using a delicate balance between visual identification and odor to make the assessment.

The scientists studied 50 colonies of L. flavolineata in Peninsular Malaysia. To test resident wasps for visual-only recognition, they used nest mates (proper colony members) and alien wasps (from outside the colony "neighborhood") that were essentially washed clean of their chemical scent.

To test the resident wasps for their reaction to scent-only, the researchers used filter paper drenched in either the extracted scent of either nest mates or rogue alien wasps.

The researchers found that when the resident wasps in a colony had to rely on scent information alone, they were more inclined to mistake an enemy for a friend. Plus one for intruders, but not so good for the colony. On the other hand, when the wasps had only facial recognition to go on, they were more likely to attack friendly colony-mates by accident. Hmm. Not ideal either.

The wasp's solution? Strike a balance between sight and scent, but place a higher priority on visual cues and attack anyone you think doesn't look right.

The upside of the visual, "hit first and ask questions later" approach, the scientists found, is that the attacking wasp will realize it is mistaken and abort the battle before seriously injuring its colony-mate.

"These wasps can use both face recognition and scent to determine whether another wasp is friend or foe," explained one of the paper's co-authors, Dr. David Baracchi, research fellow at QMUL. "Unfortunately, neither sight nor smell is infallible so they appear to not take any chances and attack anyone whose face they don't recognize."

While the idea that wasps can be pretty good at recognizing the faces of other wasps was known, the study is the first to show that they use facial recognition as the determining factor when deciding whether or not to attack what they think is an intruder.

Read more at Discovery News