London, Dec 21 (ANI): Female spiders eat their male partners after sex only if they are starving, a new study has found.
Scientists at Miami University, US, have shown that relative to their normal prey, male spiders are not very nutritious, and female sexual cannibals only eat them if they are the last resort to avoid starvation.
Dr Shawn Wilder and Professor Ann Rypstra of Miami University in Hamilton, Ohio, investigated how nutritious a meal a male wolf spider is for a female.
After around one in three matings, a female wolf spider eats the male.
The researchers measured how much of a male spider a female typically eats, including the proportion of lipids and proteins consumed from his body.
They compared that to how much a female spider eats of a more usual prey, a house cricket.
The researchers found that female wolf spiders typically eat 72 percent of the biomass of a cricket compared to just 51 percent of male spiders.
They also sucked out much more lipids from crickets, than from their former mates.
Around 20 percent of a cricket's body is lipids, while just 5 percent of a male spider's body is lipids.
The study found that eating males does not provide female spiders with the nutrition required to successfully reproduce.
"Our results show that females need a lot of lipid to produce eggs, yet the male spiders have very little lipid in their bodies. Males are a less nutritionally balanced food item for females than other prey items like crickets," the BBC quoted Wilder as saying.
"I was surprised by the results because sexual cannibalism has often been thought of as a nutritionally-motivated decision. Instead, our results suggest that cannibalism may [provide] a low quality meal that may be a last resort to avoid starvation," Wilder added.
The study has been published in the journal Oecologia. (ANI)