Thread by @MalekRobert

A few words on how this spray is generated and why the #beetle is not harmed in the process:

Hydroquinone and hydrogen peroxide are secreted by specialized glands and stored in a tank. Other glands produce catalyst enzymes such as catalases and peroxidases. 1/7

https://twitter.com/MalekRobert/status/1512447713815711750

When the contents of the two glands are mixed, oxygen forms and in turn reacts with hydroquinone to convert it to benzoquinone. Pressure due to the buildup of oxygen then causes the hot mixture of water and benzoquinone to be expelled. 2/7

The explosion chamber is made of a mixture of chitin, proteins and waxes, which protect the beetle’s soft interior from the chemical mix, the high temperatures and the pressure. To withstand the #explosive force, the blast consists of a series of micro-pulses. 3/7

Why the beetle ejects its defensive spray in pulses as opposed to one, dramatic blast? First of all, the attack can be sustained for a longer period of time and has a wider range. Also, the beetle's body can cope with multiple smaller forces better than one greater force. 4/7

The beetle aims accurately at its own body parts, in response to attack. Grab one of the beetle’s lower leg segments, and the boiling spray will be directed exactly at that segment, even if the entire abdomen must be twisted to point the nozzle in the right direction. 5/7

This ability is thought to have #evolved as a defense against #ants, which can attack from any direction. 6/7

The beetle's cuticle is not harmed by these pulses thanks to the same mixture of chitin, proteins and waxes that make up the explosion chamber.
#chemical_warfare #defense_mechanism #insects
Dean et al. 1990: lnkd.in/dzwY7Yn7
Arndt et al. 2015: lnkd.in/dTz-CU2f

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