Most insects live in constant fear of predatorsābut not the velvet ant. New research suggests that these gaudy, fuzzy insects are essentially invincible.
Velvet ants are actually wasps whose wingless females walk in search of other wasp and bee nests to parasitise. Though theyāre slow, theyāre bristling with deterrentsāa tank-like exoskeleton, foul chemical excretions, and a sting so painful theyāre often called ācow-killers.ā
Brian Gall, at Hanover College in Indiana, wanted to see if anything can actually eat velvet ants. His team set up feeding trials with likely predators found in the same habitats, including a lizard, shrew, mole, bird, and an American toad.
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Almost none of them managed to eat a live velvet ant apart from one of the toads which appeared to immediately regretĀ its decision. The toad appeared to stop breathing for 20 seconds and its body twitched as it appeared to try and regurgitate the ant. When presented with another ant later, it swiftly backed away.
Even the lizard, which is accustomed to eating stinging and venomous bees, ants and wasps, couldnāt handle the velvet ants, Gall says.
Ouch ouch ouch
The ants appear to use three distinct phases when deterring predators: preventing biting injury by being too hard to crunch, stinging, and then once relinquished, reinforcing how inedible they are with smells, and a squealing sound they make by rubbing two parts of their abdomen together.
āThe research shows how a suite of defenses is almost always stronger than a single defense, even a single defense that is exceedingly powerful,ā says Justin Schmidt, an entomologist at the University of Arizona who was not involved in this study.
Gall says these defences could have partly evolved to deal with the guards in the nests velvet ants parasitise, but he thinks their exposed lifestyle drove the adaptations.
āYouāve got this insect thatās slow, walking around on the surface during the day, so predation risk is going to be really high,ā he says.
Either way, velvet ants have seemingly conquered all assailants.
āIn most predator-prey interactions, the predators evolve special abilities to eat well-defended prey,ā says Joseph Wilson, an evolutionary ecologist at Utah State University and coauthor on the study, citing how even scorpions and poisonous newts fall victim to specialised predators.
āBut the well defended velvet ant seems to have no predator that can effectively eat it.ā
Ecology and Evolution
