2 years ago
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Male mason wasps person nary sting, but they person spines connected their genitals that tin origin a pricking pain, and these are effectual astatine deterring immoderate frogs from eating them
Life 19 December 2022
Female wasps person a venomous sting to discourage predators, but males deficiency this protection. Now, researchers person discovered that antheral mason wasps have an alternate defence strategy: utilizing their spiky genitals to onslaught animals that effort to devour them.
Male wasp genitals see an aedeagus, the insect mentation of a penis, and a brace of parameral spines. In immoderate different insect species, akin organs injure females during mating to forestall her from mating again. But mason wasps (Anterhynchium gibbifrons) observed mating successful a laboratory don’t look to usage these spines against their mates.
Shinji Sugiura astatine Kobe University, Japan, says his squad decided to research whether the spikes were alternatively utilized for defence aft his workfellow Misaki Tsujii was “stung” by a antheral mason wasp, adjacent though the males person nary existent sting.
“The antheral wasp utilized a brace of crisp spines successful the genitalia to pierce her finger,” says Sugiura. “Surprisingly, the antheral ‘sting’ caused a pricking pain. I hypothesised that the antheral genitalia of A. gibbifrons relation arsenic an anti-predator defence.”
The squad placed azygous antheral wasps successful a instrumentality with either a histrion frog (Dryophytes japonicus) oregon a pond frog (Pelophylax nigromaculatus). On each occasion, the frog attacked the wasp. But portion each of the pond frogs successfully ate the wasp, the histrion frogs rejected it 35 per cent of the time.
The wasps were often observed to pierce the rima oregon look of frogs with their genitalia portion being attacked. In different test, histrion frogs were enactment successful a instrumentality with antheral wasps that had been castrated with forceps, and they each ate the wasps.
“Because wasps and bees evolved venomous stings from ovipositors [the conduit utilized to laic eggs], their males, which deficiency ovipositors, were believed harmless. However, we recovered that antheral wasps usage the genital spines to counterattack predators,” says Sugiura.
When pistillate wasps were tested instead, each of the pond frogs ate them, but 87.5 per cent of the histrion frogs rejected them, showing that their stings are much effectual than the antheral genital defences.
The “sting” of antheral wasps had been documented before, scoring a level of 1 connected the Schmidt sting symptom index, compared with 1.5 for pistillate stings. But this probe was the archetypal to usage existent predators to trial the spines’ purpose.
Journal reference: Current Biology, DOI: 10.1016/j.cub.2022.11.030
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