They say that food is the way to a man’s heart. Not so with hunting spiders. In the arachnid world, it’s the males who seduce potential mates with tasty food morsels.
Previous studies have shown that these “nuptial gifts” improve a male spider’s chance of fathering spiderlings and reduces the likelihood of being eaten post-copulation. In fact, males could up their chances of survival by a staggering 600 percent if they come bearing gifts. Now, new research published in the journal Behavioural Ecology and Sociobiology suggests that this practice is even more important than previously thought.
Unlike the vast majority of species who use sex pheromones to attract mates, the Pisaura mirabilisi female is entirely indifferent to the chemical signals of male spiders. Instead, it is their edible offering that gets them all hot and bothered.
Researchers from the Ludwig Maximilian University in Munich, Germany, conducted two experiments on approximately 100 individual Pisaura mirabilisi, commonly known as the nursery web spider, to determine the effect of male and female silk on mating selection.
Whereas most spiders use silk to create intricate webs, the nursery web spider is a wandering species. Instead of webs, they produce draglines that hang on branches or trail behind them. As well as providing an effective way to get around, these draglines attract potential mates.
Males also use this silk to gift wrap snacks for their mating partner to eat during copulation. It is one of the very few species of spider to engage in this sort of behavior.
In the study, it very quickly appeared evident that male and female spiders respond very differently when exposed to silk from members of the opposite sex.
In females, the silk acted as a calling card or lonely hearts ad, attracting males to the vicinity and alerting them to a potential mating partner.
In sharp contrast, the female spiders couldn’t care less about the silk produced by males, whether it was from their draglines or the wrapping paper to the nuptial gifts. This led the researchers to conclude that either male Pisaura mirabilisi do not give off chemical signals like pheromones or females have learned to ignore these signals because male spiders use them to fool the female on the size and quality of the meal on offer.
"This suggests that males rather may be uniquely exploiting females' interest in food through their gift-giving behavior,” Michelle Beyer, co-author of the paper, said in a statement.