Male wasps use spiky genitals to defend themselves from predators

Male mason wasps haven’t any sting, however they’ve spines on their genitals that may trigger a pricking ache, and these are efficient at deterring some frogs from consuming them

By Matthew Sparkes

Female wasps have a venomous sting to discourage predators, however males lack this safety. Now, researchers have found that male mason wasps have another defence technique: utilizing their spiky genitals to assault animals that attempt to eat them.

Male wasp genitals embrace an aedeagus, the insect model of a penis, and a pair of parameral spines. In another insect species, comparable organs injure females throughout mating to forestall her from mating once more. But mason wasps (Anterhynchium gibbifrons) noticed mating in a laboratory don’t appear to make use of these spines in opposition to their mates.

Shinji Sugiura at Kobe University, Japan, says his workforce determined to discover whether or not the spikes have been as an alternative used for defence after his colleague Misaki Tsujii was “stung” by a male mason wasp, although the males haven’t any precise sting.

“The male wasp used a pair of sharp spines in the genitalia to pierce her finger,” says Sugiura. “Surprisingly, the male ‘sting’ caused a pricking pain. I hypothesised that the male genitalia of A. gibbifrons function as an anti-predator defence.”

The workforce positioned single male wasps in a container with both a tree frog (Dryophytes japonicus) or a pond frog (Pelophylax nigromaculatus). On each event, the frog attacked the wasp. But whereas the entire pond frogs efficiently ate the wasp, the tree frogs rejected it 35 per cent of the time.

The wasps have been often noticed to pierce the mouth or face of frogs with their genitalia whereas being attacked. In one other take a look at, tree frogs have been put in a container with male wasps that had been castrated with forceps, and so they all ate the wasps.

“Because wasps and bees evolved venomous stings from ovipositors [the tube used to lay eggs], their males, which lack ovipositors, were believed harmless. However, we found that male wasps use the genital spines to counterattack predators,” says Sugiura.

When feminine wasps have been examined as an alternative, the entire pond frogs ate them, however 87.5 per cent of the tree frogs rejected them, displaying that their stings are simpler than the male genital defences.

The “sting” of male wasps had been documented earlier than, scoring a stage of 1 on the Schmidt sting ache index, in contrast with 1.5 for feminine stings. But this analysis was the primary to make use of actual predators to check the spines’ function.

Journal reference: Current Biology, DOI: 10.1016/j.cub.2022.11.030

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