Parasitic wasp larva gets more than a meal from its spider host

In a study featured in the Journal of Experimental Biology, Kobe University researcher Keizo Takasuka and his colleagues gathered specimens of a species of spider known as Cyclosa argenteoalba. The spiders worked on this web for approximately 10 hours, and it was finished just in time before the larvae of the wasp begin to pupate. The wasp larvae drain the blood and guts of the host spider, leaving it literally a husk of its former self.

Professor Austin is an expert in parasitic lifestyles of insects. However, when the wasp lays its eggs on the spider, the spider will retreat and hide whenever the wasp wants, not during the spider’s molting stage. This was done by laying the wasp eggs either on the spiders or within their body.

“This is their modus operandi, this is what they do”, Professor Austin said. Thus, it is safe to say that the infected spider will not only serve as a home builder but also as food to the wasp’s offspring. This will happen right before the larvae are about to pupate, the researchers noted during their study. These webs were reported to be enormously strong, even compared to the spider’s usual web.

While the spiders are building the nests, the web that is the basis of the wasp’s nests is 2.7 to 40 times stronger than any web build by the spiders under normal conditions. Furthermore, the injected substance may also interact with the spider’s endocrine system, which would explain the very frenzied and unusual web building. The spiders are coerced to reinforce the threads they used either by the poison the wasp injected initially, by something injected into them by the larvae, or by a combination of the two, effectively removing the free will of the spiders and transforming them into zombies. These stronger webs can support a wasp cocoon. These arachnids were located in different shrines around the cities of Sasayama and Tamba. When the wasp larva hatches, it hijacks the spider’s behavior – maybe through a bite that delivers a chemical cocktail resembling the spider’s natural molting hormones. The researchers collected the spiders and brought them back to their lab. There, they made video recordings of them constructing their cocoon webs.

Upon closer examination of the spider specimens, the researchers found that some of the insects have been previously parasitized by a wasp known as Reclinervellus nielseni.

This wasp can be found in certain parts of Australia and it is not the only one that can prompt behavioral changes.