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Male wolf spiders 'mate with virgins and cannibalise older females'


April 13, 2011 - London

Scientists, led by an Indian-origin, in Uruguay have discovered that male wolf spiders mate with virgins and eating older females.

In several species, female spiders are known to eat males after mating, but this is the first time biologists have seen the roles reversed in the wild.

According to BBC, the species in question, Allocosa brasiliensis, is a nocturnal wolf spider found in South America.

After observing a male spider eating a female in the wild, Anita Aisenberg and her team from the Clemente Estable Institute of Biological Research, Montevideo, set out to find an explanation for the behaviour.

Aisenberg said that in most species of spider the females are larger than the males and are the selective sex, while with the wolf spiders the males are unusually dominant.

Researchers observed male wolf spiders waiting in their burrows for visiting females looking for a mate before either mating with them or eating them.

'This is not only the first report for spiders, but also extremely rare for the animal kingdom,' the Daily Mail quoted Aisenberg, as telling the BBC.

Sexual cannibalism has been widely documented in spiders, and some other species such as the praying mantis, and it is also the case that spiders eat other spiders as prey in the normal course of their lives.

Some scientists believe that sexual cannibalism may have arisen solely due to lack of food available for foraging.

But in what the researchers described as an 'extreme sexual choice', the male wolf spiders appeared to be selecting whether to mate with females or eat them - a choice that appeared to be based on their mating potential.

Males mated more frequently with virgins with high body condition, as a way of ensuring a future successful progeny, said Aisenberg.

'Females with better body condition will provide more eggs and, consequently, more sons and daughters,' she said.

Older females, and those with lower body condition, were more likely to end up being supper.

Researches believe the environment in which the spiders live may have moulded their unusual sexual behaviour.

The habitat of the wolf spiders can be harsh with extreme temperatures and strong winds.

ANI

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