A new study published in the Journal of Experimental Biology indicates that wasps can turn spiders into zombies in order to force them to construct a home for them using their web-spinning abilities. Moreover it seems that the webs the spiders produce when they are zombies are stronger than the ones they usually produce while molting.
Only certain parasitic wasp larvae are able to do this; the species is known as Reclinervellus nielseni and it infects the species of spider called Cyclosa argenteoalba. The wasp dive-bombs the spider and afterwards stings it causing it to paralyze temporary. After the spider is immobilized the wasp injects it with an egg or glues to egg to the spider’s belly and flies off. The egg hatches into a larva in a few weeks. It grows by making small holes in the belly of the spider in order to suck its blood. In the last stage of the larva’s development it sucks the spider dry and afterwards makes it spin a web for the larva’s cocoon.
This occurs right before the larva pupates. The wasp uses a special hormone in order to make the spider do the bidding. When it is infected the spider tirelessly beings to build the web which is between 2.7 and 4 times stronger than the normal web although is not as effective for catching food. Once the web is built the wasp larva moves there and uses to cocoon in order to fully pupate. Finally the wasp lures the spider in the center of the web to kill it.
This species of spider usually forms two types of web: circular sticky web which helps them catch the prey and resting web which is stripped-down and not sticky. The researchers noted that in most cases the larva made the spider produce altered versions of resting web. It was also observed that the cocoon was formed of web which was stronger than the two other types of web that the spider usually produces.
The research team was able to observe all this after analyzing over 1600 spiders in south-central Japan, near the cities of Sasayama and Tamba. They identified that 23 of the spiders had parasitic larvae. These were taken to the lab where scientists took videos of them while they were spinning the cocoon webs and afterwards compared their behavior with the one of normal spiders.
Image Source: National Geographic