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Scorpions Adjust Venom to Predators and Prey

Scorpions can fine-tune their venom to suit different predators and prey, a study published in Proceedings of the Royal Society B has reported.

Dr Jamie Seymour of The Australian Institute of Tropical Health and Medicine at James Cook University said that varieties of scorpion toxin worked better depending on whether they were used to protect themselves from predators or kill prey. A typical scorpion predator would be a small mammal, while its prey was usually an insect.

“Scorpions contain three separate subtypes of toxins that are effective against mammals only, insects only, and both,” Seymour said. The venom produced can be thought of as a cocktail of the different toxins. “The question was whether the ‘recipe’ for this cocktail is fixed or can adapt in response to different environments and predator–prey interactions.”

The research team kept Australian rainforest scorpions under different conditions. One group was given live crickets, another was given dead crickets, and a third group was subjected to the threat of a stuffed mouse to simulate a predator threat. After 6 weeks, scorpions exposed to the simulated predator exhibited significantly different venom chemistry compared with those not exposed to predators.

“Exposure to a simulated predator appeared to decrease relative production of toxins that would work on insects, while generally increasing the production of a section of the venom profile with activity towards mammalian cells,” said co-author Dr Tobin Northfield.

Seymour believes this is the first time researchers have reported that venom chemistry in organisms can change in response to a threat. “It implies a re-routing of nutritional or energetic resources by the scorpion to increase relative production of different venom fractions which are responsible for toxicity to invertebrates,” he said.

Seymour said the finding opened up the potential for improvements in anti-venom design.