If there’s one thing that we have all learned from the Discovery Channel and from Animal Planet, is that nature is cruel. It may come in a great many shapes and sizes, but cruelty is a very big part of nature and it is essential to survival in the wild and to the world as we know it.
Parasitoid arthropods are among the world’s cruelest creatures, because they always kill their hosts, but taking into account the horrendous ordeal that they put them through beforehand, death is ultimately less of a punishment and more of an act of mercy. Parasitoid wasps have a series of gruesome tactics that they employ to ensure the survival and the fitting development of their offspring.
The wasps generally jab other small creatures, ranging from caterpillars to flies and even spiders, and they place their eggs inside the host along with this deep sting. Then the devilish larvae hatch and begin to eat of their host more and more, until they are developed enough to make their way out.
Up to that point, the larvae use the host for defensive purposes as well, so that they can grow stronger and stronger until they are strong enough to move on, at which point they burrow their way out of their host, killing it on the spot or leaving it drained of energy and nutrients and exposed to predators and disease.
But Reclinervellus nielseni has an entirely different technique. The adult female wasp simply places her eggs on a spider and she flies off, because her role is essentially completed.The species of spider featured in the study was Cyclosa argenteoalba.
The eggs hatch and small larvae come out that are absolutely thirsty for survival and so, they will latch on a more exposed spot on the spider’s surface and begin consuming its haemolymph for their own growth.
Then they simply remain attached to the spider as exo-parasites, but they ensure that the spider works in their advantage by injecting a very potent chemical in the spider’s system as they feed.
This chemical has the capacity to generate an exacerbated web building activity in the spider, that beings working on a much stronger version of a web that it normally uses when it passes through its numerous development phases.
This particular type of web is not sticky at all and so, it does not attract any other insects and arthropods towards it. When the spider is done with the web, the larvae has one last use for it and so.
As the larvae is already quite large in size by that point, it is able to extract all of the spider’s haemolymph in a swift and aggressive move that looks as if it were deflating a balloon, because at the end of it, the spider is literally dried out of all of its fluids.
The larvae is then appropriately fed and it has safe accommodation for the next stages of its development, thus making the spider a sort of bed and breakfast on its journey towards adulthood.
This amazing study was conducted in Japan by the Kobe University and its impressive findings were published in the Journal of Experimental Biology.