Date From Hell: Some Male Spiders Eat Females After Mating
Most of us have heard of black widow females eating the males after they mate, but I’ve personally never heard of the opposite. Sexual cannibalism is a somewhat common practice seen in the insect and especially the spider world. This is the ultimate date from hell, with females usually consuming their male partner before, during, or after mating. It seems like in the insect world it’s all the females eating the males. However, a new discovery by scientists has found that a certain species of male spider reverses this role and eats the female after mating rather than the other way around.
Male sexual cannibalism has now been observed in the ground spider species Micaria sociabilis, and scientists believe they’ve also found another species of spider, Allocosa brasiliensis also practices male sexual cannibalism. What scientists are trying to understand is what motivates this practice.
The M. sociabilis spider is a small brown spider that commonly lives in trees in Central Europe. They have two times a year when they mate and produce offspring, once in the spring and once in the early summer. Females born in the spring generally survive long enough to participate in the second mating period. In May the number of males drops swiftly, which researchers believe is a factor that contributes to the male sexual cannibalism. The males pretty much have their pick of females to mate with during this time due to their drop in numbers, giving them the advantage in the competition to find a mate. They have the choice over what size and quality of the female they will choose to mate with. Males can mate with older females from the spring mating season or choose virgin females from the new summer generation.
In a recent study researchers tried to see if any of these factors contributed to whether a male would eat his mate by pairing up males with females of different size and age. The larger males were found to be more aggressive and likely to attack a female and eat her no matter what her age and size. On the whole, however, males were more likely to attack females from the older, spring generation. The frequency of the cannibalism also changed depending on the time of year. While we usually think of females as being the choosy gender, in this case the males are the picky ones. They also show that picky side in a rather extreme way, buy attacking and eating the females they found that did not meat their standards. Talk about the ultimate date from hell!
Do you know of another species of insect or animal that practices sexual cannibalism? Which gender is the unlucky victim?