Animals look for many things in prospective partners: showy feathers, massive racks, or even thirst-quenching sperm. But most of the time, the partner being alive is non-negotiable. Not so, apparently, for the two-spotted spider mite. In a frankly bizarre turn of events, males appear to pick dead infected females over their still living counterpart.
Researchers from the Norwegian Institute for Agricultural and Environmental Research wanted to find out what the male insects (Tetranychus urticae) looked for in a mate. Giving a whole new meaning to drop-dead gorgeous, they found out to their surprise that if given a choice between a healthy immobile female, and a dead one infected with the fungus Neozygites floridana, the males spent more time with the corpses. The study is published in Science Direct.
Normally, sex for the spider mites is a waiting game. When a male finds a female in her second larval stage, he’ll stick about guarding and caressing her whilst she can’t escape. As soon as she reaches sexual maturity and begins shedding, he’ll help her remove her exoskeleton in a weird version of insect sexual grooming. And that’s when he pounces, as it’s often the first sperm from the first mating that fertilises the eggs.
Whilst the researchers say in their paper, “we are not aware of any other example of males consistently preferring dead females to living ones in choice test,” there are not alone in the animal kingdom for their necrophiliac tendencies. Those cute and cuddly sea otters? Yep, they rape baby seals to death. The mallards you feed in your local pond? They’ve been found engaging in homosexual necrophilia. And don’t even get started on the Amazonian frog Rhinella proboscidea.
In general, most animals don’t benefit from caressing cadavers, so it’s unclear as to what’s driving the spider mites desire here. One possibility is that they simply don’t know the females have kicked the bucket. “[Another] hypothesis could be, however, that the pathogenic fungus is producing chemicals that are attractive to spider mites,” Nina Trandem who led the research told the New Scientist.
This wouldn’t be the first time that insects were drawn to their death by sexy smelling chemicals. The bolas spider doesn’t build a web, instead it gets its prey to come to it by smelling like female moths to lure in some poor unsuspecting males. It wouldn’t be that surprising then if the fungus was simply trying to attract its next host.
Either way, preferring to bed down with a body is not going to be a particularly good survival strategy, and things don’t seem that different for this fatal attraction.
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