Giant Amazonian wasp species discovered that can zombify spiders’ minds

15 Jan 2020

The tropical parasitoid Acrotaphus wasps manipulate the behaviour of their host spiders in a complex way. Image: Kari Kaunisto

Researchers have discovered a new wasp species that can take over the brain of spider prey to protect its offspring.

Researchers from the University of Turku in Finland and a Brazilian Amazon research group have discovered 15 new massive species of parasitoid wasps (Hymenoptera) in the lowland rainforests of the Amazon and the cloud forests of the Andes. These wasps prey on nearby spiders.

Females attack the spider, hijack its nervous system and force it to build a cocoon to protect the wasp’s young. Once this is built using the spider web, the wasp larva will eat the helpless spider before breaking free of the cocoon.

The insects are one of the most species-rich animal taxa on Earth, but their tropical diversity is still poorly known. These latest findings were published to Zootaxa.

Among the newly discovered wasp species was Acrotaphus, which really caught the attention of the researchers. This is because of their size, with them being able to grow multiple centimetres in length, as well as being very colourful.

Diego Pádua, lead author of the new study, said that until now, only 11 species of the genus were known. This latest discovery gives significant new information on the diversity of insects in rain forests.

Spinning a special web

Ilari E Sääksjärvi of the University of Turku said that Acrotaphus was particularly interesting because it is able to manipulate the behaviour of the host in a complex way.

“During the time period preceding the host spider’s death, it does not spin a normal web for catching prey,” he said.

“Instead, the parasitoid wasp manipulates it into spinning a special web which protects the developing pupa from predators. Host manipulation is a rare phenomenon in the nature, which makes these parasitoid wasps very exciting in terms of their evolution.”

Among the few other examples of host manipulation is a fungus that invades the nervous system of a fruit fly and then eats it from the inside out.

Before the fly meets a grisly end, the fungus is able to take control of the creature’s body and force it to reach a high point and spread its wings. In doing so, the fly’s abdomen is exposed, allowing the fungus to shoot out its spores from the dying fly at a great height, possibly infecting new flies.

Colm Gorey was a senior journalist with Silicon Republic