Wasp Masters Manipulate Zombie Spider Slaves
If you think your life's bad, consider a spider that's turned into a zombie, brainwashed into building a home, and then killed when the job's done.
Proving that reality can be stranger than fiction, a new study describes how larvae of a clever, yet ruthless, wasp turn their spider victim into a zombie before forcing it to frantically build them a home. When the spider's usefulness ends, the larvae kill it.
The discovery, which is reported in The Journal of Experimental Biology, represents one of the most extreme acts of host manipulation by a parasite.
The wasp's secret weapon is what the authors describe as an "unusual concentration" of "a manipulative substance," which they suspect is a hormone.
Keizo Takasuka of Kobe University and colleagues made the determination after collecting spiders from the species Cyclosa argenteoalba. The researchers found the spiders at shrines in the cities of Tamba and Sasayama in Japan. Once captured, the spiders were brought back to a lab and observed.
The researchers noticed that some of the spiders had previously been parasitized by the wasp Reclinervellus nielseni. To do this, the wasp laid eggs either on or within the spider's body.
Then, something really strange happened.
Each of the wasp-infected spiders worked tirelessly for around 10 hours to build an incredibly strong web, complete with a cocoon and even glistening silken "web decorations." All of this happened just before the wasp's larvae were about to pupate.
The webs contained so many fibers that they were anywhere from 2.7–40 times stronger than the spider's usual webs, meaning the ones that the spider normally creates for itself to rest on and to catch prey.
Once the special webs were built, the wasp larvae moved in, using the spider-made cocoon to pupate. They then lured the spider to the hub of the web. Once there, the hapless spider was killed.
Takasuka and the other researchers suspect that the wasp larvae inject a compound into their spider victim. It is comparable to one that the spider naturally produces. The authors write that "the manipulative substance may react with the spider's endocrine system," leading to the hyperactive and unusual web-building behavior.
Other parasites control the behavior of their hosts for selfish reasons. For example, horsehair worms develop inside the bodies of crickets and grasshoppers. The worm parasites manipulate the behavior of their hosts, often causing them to jump into streams, where the adult worm emerges and goes off on its own before starting the whole cycle again.
In humans, certain parasites can multiply in the brain, leading to behavioral changes that may include everything from memory loss to self-mutilation.
The spider Cyclosa argenteoalba, which becomes a zombie slave to the wasp Reclinervellus nielseni.
You almost feel for them, spiders. They can't help being what they are, and yet almost no one is happy to see them. Especially true when they have exceedingly long legs, thick bodies and a general mien that makes you turn quickly in some other direction. Photos don't bite, though, so let's take a look at some honking-big spiders -- with Halloween on the way, we may as well get started freaking ourselves out. Shown here is the Brazilian wandering spider (a.k.a.
), a feisty and venomous crawler from South America. Just four years ago it took home an award from the Guinness World Record people for the title of "most venomous" spider. This spidey's legs can span nearly 6 inches, its body just shy of 2 inches. It gets its name thanks to its preference for strolling along the tropic floor at night seeking out prey, rather than building webs or hiding out someplace waiting to strike. During the day, it lays low wherever it's convenient -- even inside banana plants, which is how it get its nickname "banana spider."
Not to be outdone is a spider that's been making a big splash of late, with an entomologist's
. It's called the Goliath bird-eater (a.k.a.,
). It can weigh in at almost 6 ounces and it's been known to reach nearly a foot in leg-span. The "bird eater" moniker must be there to warn birds away, though, because this spider doesn't typically eat birds as a matter of, er, course. It will regularly eat small land animals such as frogs, lizards, and snakes, however.
Meet the golden-silk orb weaver spider. Step into its parlor, if you must. Don't be fooled by its deceptively gentle-sounding name. The female golden-silk orb weaver's body alone can reach 2 inches, its legs can stretch to more than 5 inches, and it's even been observed killing and eating tree snakes. What's more, a study published earlier this year found that these spiders, when living in urban areas,
than usual. Interesting side-note: The golden-silk orb weaver also belongs to the oldest surviving genus of spiders,
, which has a fossil in the record that dates to 165 million years ago.
The Brazilian salmon pink bird-eating tarantula has a leg-span that can reach 11 inches and weight that can tip the scales (well, for a spider) at about 3.5 ounces. Despite its name, it's not confirmed that they actually eat birds any more than do the Goliath bird-eaters. Instead, they dine on insects or the random small amphibian or reptile. Instead of making a web, it takes its prey by quick-strike ambush in the open.
The giant huntsman spider is so big it even took the trouble to have a size descriptor built into its name (given that Goliath was taken). The huntsman is neck and neck, or leg and leg, with the Goliath bird-eater for the title of biggest spider, by leg-span (in sheer body mass, though, the Goliath is more like an offensive lineman, while this spider is a lanky cornerback). A giant huntsman's legs can stretch out to 12 inches, and its speedy, crab-like gait makes it a fast hunter that excels at chasing down its meals. It hails from caves in Laos.