Researchers have discovered 15 new wasp species in lowland Amazon rainforests and Andean cloud forests that parasitize spiders in a “complex way.”

Female Acrotaphus wasps are known to attack spiders in their webs, temporarily paralyzing the arachnids with a venomous sting so they can lay a single egg on a spider. The wasp larva then hatches from the egg and gradually eats the spider before it pupates.

According to study co-author Ilari E. Sääksjärvi, a professor of biodiversity research at the University of Turku, the 15 newly discovered species of Acrotaphus wasps control host spiders’ behavior in very particular ways in order to ensure the survival of their offspring.

Researchers have discovered 15 new wasp species in lowland Amazon rainforests and Andean cloud forests that parasitize spiders in a “complex way.”

The discoveries were made by a research group with the Biodiversity Unit of Finland’s University of Turku, which has studied tropical parasitoid insect diversity for the past two decades, in collaboration with researchers at Brazil’s Instituto Nacional de Pesquisas da Amazônia (INPA).

The new species, all of which are wasps of the genus Acrotaphus that parasitize spiders, are described to science in a study published in the journal Zootaxa last month.

“Acrotaphus wasps are fascinating because they are very sizeable parasitoids,” Diego Pádua, a postdoctoral researcher and lead author of the study who has worked at the INPA and the Biodiversity Unit of the University of Turku, said in a statement. “The largest species can grow multiple centimetres in length and are also very colourful. Previously, only 11 species of the genus were known, so this new research gives significant new information on the diversity of insects in rain forests.”

Female Acrotaphus wasps are known to attack spiders in their webs, temporarily paralyzing the arachnids with a venomous sting so they can lay a single egg on a spider. The wasp larva then hatches from the egg and gradually eats the spider before it pupates.

Members of the genus Acrotaphus aren’t the only wasps that parasitize spiders. The genus Idris includes more than 300 species of wasps that parasitize spider eggs. But, showing just how little we know about these insects, an Idris wasp was discovered late last year in Mexico parasitizing an invasive stink bug — the first Idris species ever discovered to do so. That species was given the scientific name Idris elba.

According to study co-author Ilari E. Sääksjärvi, a professor of biodiversity research at the University of Turku, the 15 newly discovered species of Acrotaphus wasps control host spiders’ behavior in very particular ways in order to ensure the survival of their offspring.

“The Acrotaphus wasps we studied are very interesting as they are able to manipulate the behaviour of the host spider in a complex way,” Sääksjärvi said in a statement. “During the time period preceding the host spider’s death, it does not spin a normal web for catching prey. Instead, the parasitoid wasp manipulates it into spinning a special web which protects the developing pupa from predators.”

This is what makes the wasps truly intriguing discoveries, Sääksjärvi added: “Host manipulation is a rare phenomenon in nature, which makes these parasitoid wasps very exciting in terms of their evolution.”

CITATION

• PÁDUA, D. G., SÄÄKSJÄRVI, I. E., MONTEIRO, R. F., & OLIVEIRA, M. L. (2020). Review of the New World genus Acrotaphus Townes, 1960 (Hymenoptera: Ichneumonidae: Pimplinae), with descriptions of fifteen new species. Zootaxa, 4719(1), 1-62. doi:10.11646/zootaxa.4719.1.1

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