Male Mantises Wrestle to Escape Cannibalistic Females

The female springbok mantis, Miomantis caffra, is a difficult one to woo. Sixty percent of sexual encounters between springboks end in the female biting the male’s head off. A staggering difference when comparing another species of Chinese praying mantis, Tenodera sinensis, whose mating adventures end in a tasty snack only 28 percent of the time. Rather than accept their fate as other mantis species do, male springbok mantises fight females to avoid becoming a post-sex meal, according to a new study published this week in the journal Biology Letters.

Researchers Nathan Burke and Greogory Holwell of the University of Auckland in New Zealand observed a total of 52 pairs of springbok mantis for 24 hours to see which pairs fought and which one out of the couple won the battle. Over half of the mantises—26 pairs—had a scrimmage in the first 12 hours, reports Karina Shah for New Scientist.

The researchers noted that males always instigated the fights and actually used this tactic to encourage mating. When a male springbok fought against the female and pinned them down, they were more likely to mate and escape, reports Laura Geggel for Live Science. On the other hand, if the female pinned the male first, the poor guy would always be cannibalized. Out of these battles, the females came out on top about one-third of the time, and. Most of the winning males lived to see another day, with cannibalistic incidents reduced by 78 percent, reports Live Science. Females that lost the fights were severely injured by the males’ razor-sharp claws.

"When males and females are paired together, I found that males engage females in violent wrestling matches where each sex tries to be first to pin the other down with their raptor-like forelegs," evolutionary ecologist Nathan Burke says to Live Science. "Females that win the struggle always end up eating the male. But males that win are much more likely to mate instead."

Sexual cannibalism is common among praying mantises, and researchers have attributed this behavior to ensuring the survival of the female and her offspring. In Chinese mantises, females only do eat their mates when food is scarce reports, Michael Marshall, for New Scientist in 2014. For female springbok mantises, eating the male poses no threat to procreation and could give the new mother enough nutrients to also support the offspring she produces asexually. Sexual cannibalism is seen in other species like black widow spiders, scorpions, grasshoppers, and beetles.

In nature, the goal of survival is to pass on genes to offspring, so male mantises must survive to make sure they have enough love to go around.

"We think the reason males have evolved harmful wrestling behaviors is because of the enormous threat that females pose," Burke tells Live Science. "Males have to do whatever they can to avoid being eaten, otherwise they'll fail to sire any offspring. And fighting back against female aggression, even if it causes terrible injury, seems to be a very effective tactic."

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a daily correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.