AsianScientist (Aug. 18, 2015) – A study in the Journal of Experimental Biology has described a parasitic wasp that can seize control of the Cyclosa Argenteoalba spider and exploit its different web weaving behaviors.
C. Argenteoalba spiders usually build two types of webs: orb webs and resting webs. The orb web—larger and stickier—is designed to catch prey, while the resting web is simpler and not so sticky, designed for molting stage of the spider. A team led by Dr. Keizo Takasuka from Kobe University have found that a certain species of wasp can manipulate the spiders’ web weaving behaviors to its benefit.
The Reclinervellus nielseni wasp first lays its eggs on the surface of the spider’s back. When the larvae hatch, they remain attached to the spider’s body and suck on its body fluid externally. Ten to 14 days after hatching, the wasp larva starts to turn its host spider into a subordinate, manipulating the spider to spin the tougher web suitable for the wasp’s pupal stage. The wasp larva then stays on this web for about ten days until it develops to the adult stage.
Takasuka and colleagues found that the manipulated web, like the resting web, had fibrous thread decorations which use UV reflection to deter flying animals from bumping into the web of the fragile molting spider or metamorphosing wasp larva. In addition, tensile tests revealed that the center and periphery of the manipulated web are 30 times and three times stronger respectively than those of the resting web.
This study demonstrates that the parasitic wasp can induce the spider’s pre-programed behavior by interfering with the spider’s nervous system. This finding brings us one step closer to understanding the molecular mechanism of web manipulation. Takasuka expects that unveiling the molecular mechanism of spider manipulation would contribute practical applications of spider silk.
The article can be found at: Takasuka et al. (2015) Host Manipulation by an Ichneumonid Spider Ectoparasitoid that Takes Advantage of Preprogramed Web-Building Behaviour for its Cocoon Protection.
Source: Kobe University.
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