South African male praying mantises fighting back against female sexual cannibalism

Male South African praying mantises have developed a highly unusual strategy to avoid being eaten by females after mating - they're fighting back.

The praying mantids - also know as the Springbok mantis - are commonly found throughout New Zealand since first being identified here in the 1970s.

They're one of a number of insect species where sexual cannibalism by the female is common. Different insect species use different tactics to try and avoid that fate, such as playing dead when females attack.

But a new study shows the South African praying mantis will engage in "violent physical struggle" with the female to try and successfully mate.

And the strategy appears to work: the majority of males who managed to both successfully copulate and avoid being eaten engaged in physical struggle with the female.

"It is rare for males to avoid cannibalism by this form of coercion - physically fighting with females in order to successfully mate - and this is the first evidence of this behaviour in a cannibalistic mantis," says University of Auckland Research Fellow Nathan Burke.

"Sexual conflict in the insect world is not that unusual and usually favours a cautious or tactical approach but the male Springbok mantis really does fight to achieve his goal and this study shows that might be his best option in terms of reproductive success."

The research, from Dr Burke and Associate Professor Gregory Holwell of the University of Auckland's School of Biological Sciences, involved collecting 52 pairs of Springbok mantis and observing their behaviour in the laboratory over a 24-hour period.

They found 29 out of the 52 pairings (56 percent) resulted in physical contact between the sexes with the male always first to initiate contact. Almost all - 90 percent - escalated into physical struggle with 58 percent of males who managed to grab the female first ending in successful mating. Half were subsequently eaten.

A low 7 percent of pairings resulted in no clear winner from the physical contest, 35 percent resulted in the female winning the initial physical confrontation and eating the male while 20 percent of pairings resulted in no mating and no cannibalism.

Another unusual finding of the research was that 27 percent of females that lost the physical struggle were injured by the male's foretibial claws, resulting in severe abdominal puncture wounds that later formed black scabs - something also observed in females in the wild.

"We have learned a lot of fascinating biology from Miomantis caffra over the last decade, but this latest work is truly amazing," says Associate Professor Holwell.

"This is the best example out there of males fighting back to help cope with the risk of sexual cannibalism."

The research is published in Biology Letters.