New predatory bug species discovered in Aussie wilderness uses 'tool' to assassinate prey
Tool use has been associated with higher primates and humans, but a newly described Australian insect has been documented doing it too.
A new species of assassin bug has been discovered in the wilds of Australia that uses a “tool” to capture its prey. It’s one of several species scientists have documented using complex methods to attack.
Western Australian Museum insect expert Dr Nikolai Tatarnic told Yahoo News that tool use is traditionally associated with primates, dolphins and birds. But in the case of the newly described Gorareduvius gajarrangarnang it doesn’t use sticks, stones or sea sponges, but rather spends its day extracting a resin from plants and then coating itself in the sticky substance.
“Assassin bugs, as the name suggests are predators. When they attack other invertebrates the sticky resin helps them grab them more readily,” Tatarnic said.
Assassin bug discovered using resin for second reason
The assassin bug lives in two remote areas of the Kimberley. It’s been documented laboriously cultivating the resin from a soft species of spinifex, but there is some evidence to suggest it could also be stealing it from the nests of resin bees.
Along with using resin to kill, the insect also appears to be coating its eggs in the substance for two specific reasons.
“When the nymphs hatch, they have resin they can use for their first hunt. So they come out of the eggs and actually coat themselves right away,” Tatarnic said.
“On top of that, we suspect the resin probably protects the eggs from parasitoids – little wasps that would be trying to lay their eggs in the bug egg.”
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Are insects smarter than we think?
Other invertebrates create their own tools, like the bolas spider that spins a ball of web coated with fake pheromones to attract moths, and separate spider species create sticky nets to throw at prey. But fashioning tools from other substances is less common.
The use of resin by assassin bugs has been described across the Americas, Southeast Asia and Africa, but in Australia, the behaviour has been rarely seen. A separate species of assassin bug has been documented waiting at the entrance to an ant nest and slapping at them with its sticky resin-covered arms.
The emerging discoveries about assassin bugs suggest more nuanced cognitive abilities than traditionally associated with insects. Other species have been found to contain two types of venom, one kills and the other causes pain.
“The fact they can actually make this decision based on the situation of whether to use reservoir one or two shows a lot more processing power than you'd normally attribute to dumb, little bug,” Tatarnic said.
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How is the new assassin bug different to others?
Describing new species has become a faster process as technology has developed. High-resolution electron microscopes and 3D imaging make it easier to spot subtle differences, and when it comes to the insect world.
“You can look in very high detail the internal anatomy of animals. You can see the sperm storage, digestive tract and neural tissue without even dissecting the animal,” Tatarnic said.
“The scanner can go down to a resolution of 0.7 micrometres which is very small. With that you can pick up a lot of characteristics that are distorted when you put it on a slide.”
It was the reproductive organs that differentiated Gorareduvius gajarrangarnang from a similar to another assassin bug, Gorareduvius westraliensis. It also has bright orange bands on its hind legs.
How describing bugs could save the planet
As scientific tools improve, taxonomists are increasingly able to notice subtle differences in biology. Species that were thought to be just one species are frequently found to be several, once DNA is tested.
If a species hasn’t been described, then there is no mechanism to secure funding to protect it from threats like development, logging, invasive species and climate change.
“If you don't have names on organisms, they're much easier to ignore and push aside,” Tatarnic said.
“You can imagine a consultant doing an environmental report, without names, they’d only be able to say we found a lot of bugs. But once you have a name you can look at differences, whether they have a wide distribution.
“A lot of flightless insects are narrow-range endemics because they can't just disperse very readily. So they could be more susceptible to things like fire or habitat change through development.”
What does the new bug's name mean?
The Gorareduvius gajarrangarnang name means spinifex dweller. It is derived from the Miriwoong language following consultation with the Mirima Dawang Woorlab-gerring Language and Culture Centre.
The species was researched at Western Australian Museum where Tatarnic works as the curator of entomology. It was funded by the Hermon Slade Foundation, and the description was published in the Australian Journal of Taxonomy by Tartarnic on October 29 with co-authors Iria Chacón and Fernando Soley.
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