Great sex, but his mind's elsewhere…
THERE is no stopping the male praying mantids of Sydney. Even after their heads have been chewed off by their female partners, these hardy insects continue to have sex for up to eight hours.
"It's pretty cool to watch," said a Macquarie University scientist, Katherine Barry, whose research has led to an explanation for how this extreme form of sexual cannibalism may have evolved in false garden mantids, Pseudomantis albofimbriata, a species common to suburbs including Epping, Pymble and Turramurra.
By observing hand-reared mantids closely, Miss Barry has found that females benefit substantially from consuming their male partners, a job they complete after the lengthy mating has finished.
In one of the first studies able to demonstrate this effect, she found the cannibalistic females put on weight and produced more eggs using the extra energy they got from a single meal of male meat.
"Sexual cannibalism can boost the reproductive output of the females by up to 40 per cent," Miss Barry said.
Not every sexual encounter ends in death for the males, which helps explain why they keep trying. About 60 per cent of the time they do not get eaten. "Those that approach from the rear are much less likely to get cannibalised," she said.
And while about 40 per cent of trysts are fatal, in about half of these cases the males manage to copulate while being cannibalised.
The females attack first, grabbing the males by the head and thorax and chewing off their heads, Miss Barry said. "But a lot of males can use their legs to grab onto the female's abdomen and pull themselves round while being eaten and start mating with her."
The males were able to sustain sex for hours, because they have a second primitive brain in their abdomens, she said.