Beetles can escape from toad stomachs by releasing explosive chemicals

Insects capable of producing boiling hot solution from behinds that makes predators vomit them back up

Josh Gabbatiss
Science Correspondent
Wednesday 07 February 2018 01:43
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Beetle escapes from toad over an hour after being eaten

Bombardier beetles are remarkable insects with the ability to eject hot chemicals from their behinds as a defence mechanism.

The insects store two chemical compounds, hydroquinone and hydrogen peroxide, in separate compartments in their bodies.

When a bombardier beetle feels threatened, it can combine the two chemicals, resulting in a rapid chemical reaction that brings their internal solution close to 100C.

This reaction also produces gas that ejects the solution out the tip of the beetle’s abdomen and at its attacker.

Now, new research has found the beetles are capable of employing their explosive weaponry in order to escape from the digestive systems of predators.

Dr Shinji Sugiura and Dr Takuya Sato at Kobe University fed bombardier beetles, also known as Pheropsophus jessoensis, to toads to see if the insects were capable of emerging unscathed from the predators’ stomachs.

“Our experiment showed that P. jessoensis ejected hot chemicals inside the toads, thereby forcing the toads to vomit,” the researchers wrote.

“Large beetles escaped more frequently than small beetles, and small toads vomited the beetles more frequently than large toads.”

All the toads happily swallowed the beetles, but 43 per cent of the toads subsequently vomited the beetles back up.

When they emerged, the beetles were unharmed, despite some of them having been inside the toads for nearly two hours.

The results of these experiments were published in the journal Biology Letters.

Further research revealed that bombardier beetles were better able to survive the acidic digestive juices of toads than other species of beetle. This suggested the species has evolved a tolerance for digestive juices.

Another potential reason for the beetles’s survival abilities is that toxic secretions produced by the beetles decreased the toads’ digestive fluids and enzymes.

Other animals have been documented escaping from the digestive systems of their predators. Snakes have been seen escaping from inside toads, for example, and snails from inside birds.

However, the scientists noted the mechanisms underpinning these animal’s fantastic escapes have always been unclear.

The researchers predicted the escape behaviour seen in bombardier beetles is also likely to occur in other animals that produce toxic chemicals of one sort or another.

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