In Australia, “killer bugs” use a killer device to catch snacks. And recent research shows that crawlers lunge at a sticky target to catch and hold onto their prey.
Although uncommon, some insects use tools, such as ants, which use particles to build bridges. Previous reports indicate that killer insects collect plant resin, but this species uses tools more than others.
This makes killer bugs “an especially promising case for understanding the environmental conditions and behaviors that contributed to the unlikely evolution of tool use,” the researchers say.
Because tool use requires a level of sophisticated cognition, it was once thought to be a way to distinguish humans from other animals, but now researchers are finding more and more examples of tool use in the animal kingdom.
Even humans used tools before dexterity was fully developed in our thumbs, and it seems that the first tools were not even man-made.
Scientists had a premonition that the hunting success of killer beetles would increase if they covered themselves with sticky plant resin, but this was not tested in experiments.
Macquarie University biologists Fernando Soli and Mary Herberstein observed 125 Australian killer bugs of the undescribed species Gorareduvius from the Kimberley region of Western Australia in the wild and in a nearby makeshift laboratory in a tent.
Australian killer bugs usually sit on the stems of Triodia, a native weed commonly called spinifex. It is found in the dry regions of Australia and produces a sticky resin valued by early Australians for making fishing tools.
Soule and Herberstein predicted that if resin was used as a tool, resin-coated insects would be better at catching prey than non-resin-coated insects. They took 26 killer insects found near or on Triodia bitextura to their tent lab for research.
The researchers placed the insects in a glass jar using a stick and introduced two types of prey: flies and ants. Then, with the help of pads, the resin was carefully wiped off the bodies of insects, and the experiment was repeated.
Insects were generally more successful at catching ants than flies, and more importantly, they were more effective at catching prey when resin was on their bodies, regardless of the type of prey.
Resin-coated insects caught any prey 26% better than their unarmed counterparts. Flies are difficult to catch even on a good day, and without resin, 64% of the flies survived.
Both in the wild and in the lab, researchers have observed Gorareduvius removing resin from spinifex leaves and carefully applying it to its body, especially its front legs.
“Killer insects manipulate the environmental component (resin) from its normal context and apply it to their bodies, thus gaining a selective advantage through improved prey capture,” the researchers wrote.
The term “killer bug” refers to a diverse group of insects united in the gruesome way they kill their prey. The predator usually pierces the prey with its proboscis, injects it with digestive enzymes that paralyze and kill it, then sucks out the liquid contents of the prey, leaving behind an empty shell.
The study was published in Biology Letters.
Source: Science Alert
