QotW - Why are ant bites so painful?

Sally Le Page got the painful truth from insect venom expert Sam Robinson, from the University of Queensland...

Sam - Firstly, while most ants do bite, their bites are almost always inconsequential to us, it is their stings that typically grab our attention. There are ~20,000 species of ants worldwide and, like their wasp ancestor most can sting (technically, ants are just a family of wingless wasps).

Sally - Bite or sting, it still hurts. Why does it have to hurt so much?

Sam - Yes, the stings of many species can be very painful. Why? Because they have to be to survive. Ants are eusocial, that is they live in colonies. Their colonies include their young (eggs, larvae, pupae), which collectively represent a stationary and helpless nutritional bounty for a large predator e.g. reptiles, birds, mammals. Ants need to be able to defend their colony against predators in order to survive and a painful sting is a very effective strategy to achieve this.

Sally - It certainly got this large ‘predator’ away from the ant colony veerrrrry effectively. I wonder, what is in the ant venom that makes them so painful even with such a tiny sting?

Sam - Not all ant stings are equal, some are more painful than others. This reflects the different doses of venom they can deliver in their sting, and also their different venom chemistries. Some of the more painful ant stings are caused by venom molecules that (very effectively) target and over-activate a key part of our sensory nervous system, voltage-gated sodium channels, which are important for amplifying and transducing normal pain signals. Other ants use chemicals that cause pain in other ways—a variety of different chemical strategies probably exist.

Sally - There we go! And you can curse your overly activated voltage gated sodium channels next time you’ve got ants in your pants. Next week’s toes-ty question comes from Patrick:

Patrick - When I have cold feet, why won’t my brain let me sleep?