Male wasps do not have a stinger but their penis has effective thorns that they use as a weapon not to end up in the belly of their predators, reveals a study published Monday, December 19.
It was thanks to an accidental sting that Japanese scientists discovered this defense mechanism in male wasps which, unlike females, do not have the dreaded sting containing the venom.
Despite this handicap, they manage to escape their predators but through behaviors that have been misunderstood until now.
The hypothesis that certain male insects can sting with their genitals had been put forward by scientists, "
but the proof was missing
", explains Shinji Sugiura, from the University of Kobe, co-author of the study published in the journal
Current Biology
.
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This specialist in anti-predator strategies in animals had a flea in his ear when one of his students, Misaki Tsujii, co-author of the study, was stung by a male mason wasp.
"
I tried to get stung myself, and since I thought the males were harmless, I was very surprised to feel the pain of a sting
," Shinji Sugiura told AFP.
A survival strategy
He suspects the two large spines distributed on either side of the insect's penis to have caused the pain.
Hypothesis that he decides to test in the laboratory, by offering wasps as a meal to two species of tree frogs.
“
We observed many males who, at the time of the attack, pierced the mouth or other organs of the frogs with their genitals
,” he describes.
One of the videos of the attacks shows an unlucky frog trying unsuccessfully to chew the insect, before using its front paw to vigorously spit out its prey.
In total, more than a third of the predators ended up spitting out the males after being stung.
The experiment was reproduced with wasps whose genitals had been removed: the frogs made short work of them.
The difference between the situations was "
statistically significant
", which suggests that this survival strategy in males played on the evolutionary history of wasps, underlines Shinji Sugiura.
Apart from their reproductive role, the genitals of insects are still little studied.
However, previous research has shown how sphinx moths use their genitals to emit ultrasound against bats.
Shinji Sugiura has himself researched how certain beetles manage to escape once swallowed, by exiting through the anus of their predators.
The biologist now hopes to determine if other families of wasps have these same genital spikes as a defense system.