Parasitic wasp ‘zombie-fies’ spiders
VANCOUVER— In a scenario straight out of a cinematic nightmare, a newly discovered species of wasp has been found to prey on a “social” spider, turning it into a so-called zombie, which abandons its colony to become both a food source and homemaker for the wasp’s larva.
The ghastly discovery was made in Ecuador by Philippe Fernandez-Fournier, a former master’s student at UBC’s department of zoology and lead author of the study which was published in Ecological Entomology.
While other, solitary spiders are sometimes targeted for manipulation by parasitic wasps, such spiders are generally forced into behaviours they’re already likely to perform, said Samantha Straus, co-author of the study and a PhD student in UBC’s department of zoology.
“(But) this is the first time that this really interesting behavioural interaction has ever been documented with a social species, and I think that’s what makes it really cool,” she told StarMetro in a phone interview.
Normally, the social Anelosimus eximius spider will spend nearly its entire life in its colony’s basket-shaped web, cooperating on parental duties and prey capture, Straus explained. But the newly discovered Zatypota wasp species was observed laying an egg on the abdomen of such spiders, from which a larva then hatches to feed off the spider’s haemolymph (“spider blood”).
The spider — now a zombie-fied drone — then wanders off a short distance from its home and spins a dense, cocoonlike web, where it is killed and consumed by the larva.
The larva then enters the cocoon and, between nine and eleven days later,
emerges a fully formed wasp. “The wasp completely hijacks the spider’s behaviour and brain and makes it do something it would never do, like leave its nest and spinning a completely different structure,” Straus said in a statement. “That’s very dangerous for these tiny spiders.”
Straus said her team believes the hijacking may be accomplished through a hormone injection which taps in to an ancient part of the spider’s brain.