Male wasps also have a sting in the tail, using genital spines to defend themselves

Embargoed until: Publicly released: 2022-12-20 03:00

International

The pseudo-stings (parameral spines) and aedeagus of a male wasp (Anterhynchium gibbifrons). credit Shinji Sugiura

Male wasps may also have a sting in the tail, according to international research, which found that males from a particular species of wasp known as the mason wasp (Anterhynchium gibbifrons) use sharp genital spines to counterattack predators. Male wasps are generally thought to be relatively defenceless, instead opting to mimic the warning colours of female wasps which have painful stings. In this study, the researchers put tree frogs into a box with the mason wasps and observed how the wasps defended themselves. They found that due to these males jabbing the frogs with their sharp genital spines, 35.3% of the tree frogs rejected the wasps as prey. When the wasps had their spines removed, the tree frogs ate all of the wasps.

Media release

From: Cell Press

Peer-reviewed Experimental study Animals/Wasps

Male wasps use genitalia to sting their predators

Female bees and wasps use modified ovipositors, formerly used in egg laying, to sting their attackers, including people. Now, a study in Current Biology on December 19 shows that male mason wasps use sharp genital spines to attack and sting predatory tree frogs to avoid being swallowed.

“The genitalia of male animals have frequently been studied in terms of conspecific interactions between males and females but rarely in terms of prey-predator interactions,” said Shinji Sugiura, Kobe University, Japan. “This study highlights the significance of male genitalia as an anti-predator defense and opens a new perspective for understanding the ecological role of male genitalia in animals.”

Suguira and study co-author Misaki Tsujii made the discovery after an accident. Tsujii was studying the life history of the mason wasp, Anterhynchium gibbifrons, when she got stung.

“Surprisingly, the male ‘sting’ caused a pricking pain,” Sugiura said. “Based on her experience and observations, I hypothesized that the male genitalia of A. gibbifrons function as an anti-predator defense.”

Wasps and bees are, of course, well known to use venomous stings to defend themselves and their colonies against attackers. But, because they have evolved venomous stings from ovipositors, males lacking ovipositors were believed harmless. Feeling the pain of a male sting didn’t add up.

To study further, the researchers placed male wasps with a potential tree frog predator. All of the frogs attacked the male wasps, but just over a third spit them back out. The researchers witnessed the wasps stinging the frogs with their genitalia while being attacked.

When they gave tree frogs wasps that were no longer endowed with genitalia? They ate them right up.

The findings show that the male wasps use their genitalia to sting predators and avoid being eaten. Because male genital spines (called “pseudo-stings”) are found in some wasp families, they say that the newly discovered defensive role will likely be found in many wasp species.

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