Male wasps use penises as stingers, study finds

Male wasps, which don’t have a stinger, use their thorn-filled penises as a defensive weapon to avoid being eaten by predators, according to a study published on Monday.

Japanese scientists made this accidental discovery after one of them was bitten by one of these insects.

Shinji Sugiura, a biologist specializing in anti-predator strategies in animals at Kobe University, told AFP that after one of her students —Misaki Tsujii, co-author of the study published in the journal Current Biology— was stung by a male wasp, she decided to provoke a similar attack on itself.

Male wasps lack the dreaded venomous stinger, which females are busy with.

“Since I thought males were harmless, I was surprised to feel the pain of a sting,” he said.

The hypothesis that certain male insects can bite with their genitals had been formulated before, but evidence was lacking, added the scientist.

Sugiura suspected that the two large spines located on either side of the insect’s penis were responsible for the pain it produced. To test her hypothesis in the laboratory, she offered wasps to two species of frogs.

“We observed many males that, at the time of the attack, pierced the mouth or other organs of the frogs with their genitals”, he describes.

In one of the videos that record the test, one of the amphibians is seen trying to chew the insect, before removing it from its mouth with the help of a paw. In all, more than a third of the predators ended up spitting out the wasps after being stung.

When the experiment was reproduced with wasps that had their genitals removed, the frogs swallowed the insects.

The difference between the two situations was “statistically significant, which suggests that it is a male survival strategy that has influenced the evolutionary history of the wasps”, pointed out the researcher.

Apart from their reproductive role, insect genitals have been little studied until now. And it’s not for lack of interesting cases. It was discovered, for example, that sphinx moths use their genitals to emit ultrasounds against bats.

And Shinji Sugiura investigated the way certain beetles manage to escape after being swallowed by exiting the anus of their predators.

Now, the biologist intends to determine whether other wasp families have the same genital defense system.