Eating would-be mates could lead to a bigger brood for spiders, scientists have found.
The egg cases of American grass spiders that ate their suitors were compared with those that did not in a new study of pre-copulatory cannibalism.
More spiderlings of cannibalistic mothers hatched from thicker cases than non-cannibal offspring did, it showed.
It suggests an evolutionary advantage for female spiders that may eat males rather than mating with them.
The study is published in Animal Behaviour and thought to be the first to link cannibalism with reproductive success.
Aric Berning from the University of Pittsburgh, lead author of the study said that sourcing the spiders from the funnel web family was simple, because of their urban habitat.
"There were just couple of blocks we went around and would drop crickets on these funnel webs that we saw and spiders would pop out and we'd catch them."
The researchers then introduced the males to the females' spiderwebs and monitored their behaviour.
"We tracked a number of performance metrics," he said.
"The hungrier the female, the longer she had gone without food, the more likely she was to cannibalise her would-be mate. And we also found, the more aggressive the females were, the more likely they were to cannibalise a mate."
Continued: http://www.bbc.co.uk/nature/news/
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