Nav: Home

Parasitoid wasps may turn spiders into zombies by hacking their internal code

April 29, 2019

Setting off a startling chain of events, a parasitoid wasp can force a spider to weave a special web to suspend the wasp pupa just before it finishes killing its spider host. William Eberhard, staff scientist emeritus at the Smithsonian Tropical Research Institute and Marcelo Gonzaga at the Universidade Federal de Uberlândia in Brazil have assembled wide-ranging evidence that 'zombification' involves hacking existing web-spinning mechanisms by hijacking the spider's own molting hormone, ecdysone.

In a new paper published in the Biological Journal of the Linnean Society they combined a review of all known reports of different wasp species known to zombify different spider species around the world; the results from a molecular study in Brazil; and new observations of Costa Rican spiders to demonstrate several previously unappreciated patterns that suggest that the wasp larvae use ecdysone.

One puzzle the researchers address is how a single wasp species can induce an impressive diversity of changes in the webs of many different spider host species. In the most complex cases, the spider's web construction is affected at several different stages: from selecting a site to modifying several different key design elements that usually result in a sheltered, stable home for its pupal cocoon.

This feat is dramatic because the wasp larva does not have direct contact with the spider's nervous system: it is an external parasite, riding on the surface of the spider's abdomen. Its only access to the spider's brain is via injections of psychotropic substances into the hemolymph in the spider's abdomen, to then be carried by the spider's circulatory system to its central nervous system.

"Several studies suggested that sometimes the webs induced by the wasps resemble the webs that unparasitized spiders build just prior to molting," said Gonzaga. "We combined that observation with a previous discovery that, in one genus, spiders that had just built cocoon webs had unusually high concentrations of ecdysone in their bodies, and predicted that the specificity of the wasp larva's effects may already be present in the spider's nervous system, in the form of its specific behavioral responses to the hormone that controls its own molting cycle. By hacking into this system, the wasps ensure the safety of their own offspring at the expense of their host."

"Now that we have a proposed mechanism, we can ask a new set of questions," Eberhard says. "Because the lines in spider webs represent precise records of their behavior, we could study "zombification" in unprecedented detail by looking at the lines in cocoon and molting webs. We discovered that both web types vary, and more importantly, that the variations only overlap partially.

"The larvae probably tweak the spider's molting web construction behavior to gain added protection. The mechanisms by which these additional modifications are obtained may result from differences in the timing or amounts of ecdysone, or modifications in the ecdysone molecules themselves, but they remain to be documented," Eberhard continued.
-end-
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The Institute furthers the understanding of tropical biodiversity and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems. Website. Promo video.

Reference: Eberhard, W.G., Gonzaga, M.O. 2019. Evidence that Polysphincta-group wasps (Hymenoptera:Ichneumonidae) use ecdysteriods to manipulate web-construction behavior of their spider hosts. Biological Journal of the Linnean Society, https://doi.org/10.1093/biolinnean/blz044

Smithsonian Tropical Research Institute

Related Nervous System Articles:

Fewer scars in the central nervous system
Researchers have discovered the influence of the coagulation factor fibrinogen on the damaged brain.
Polymerized estrogen shown to protect nervous system cells
In research published today in Nature Communications, an interdisciplinary team from Rensselaer Polytechnic Institute demonstrated how estrogen -- a natural hormone produced in the body -- can be polymerized into a slow-releasing biomaterial and applied to nervous system cells to protect those cells and even promote regeneration.
Discovery concerning the nervous system overturns a previous theory
It appears that when our nervous system is developing, only the most viable neurons survive, while immature neurons are weeded out and die.
Autonomic nervous system appears to function well regardless of mode of childbirth
'In a low-risk group of babies born full-term, the autonomic nervous system and cortical systems appear to function well regardless of whether infants were exposed to labor prior to birth,' says Sarah B.
First step to induce self-repair in the central nervous system
Injured axons instruct Schwann cells to build specialized actin spheres to break down and remove axon fragments, thereby starting the regeneration process.
First complete wiring diagram of an animal's nervous system
In a study published online today in Nature, researchers at Albert Einstein College of Medicine describe the first complete wiring diagram of the nervous system of an animal, the roundworm Caenorhabditis elegans, used by scientists worldwide as a model organism.
Scientists unlock new role for nervous system in regeneration
Biologists have developed a computational model of flatworm regeneration to answer an important question in regeneration research - what are the signals that determine the rebuilding of specific anatomical structures?
Research gives new insight into the evolution of the nervous system
Pioneering research has given a fascinating fresh insight into how animal nervous systems evolved from simple structures to become the complex network transmitting signals between different parts of the body.
Researchers solve mystery of how ALL enters the central nervous system
A research team led by Duke Cancer Institute scientists has found that this blood cancer infiltrates the central nervous system not by breaching the blood-brain barrier, but by evading the barrier altogether.
The VIPs of the nervous system
Biologists at Washington University in St Louis unlocked a cure for jet lag in mice by activating a small subset of the neurons involved in setting daily rhythms.
More Nervous System News and Nervous System Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Clint Smith
The killing of George Floyd by a police officer has sparked massive protests nationwide. This hour, writer and scholar Clint Smith reflects on this moment, through conversation, letters, and poetry.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.