How Social Insects Use Grooming As Medical Treatment

Many people spend quite a bit of time in their life navigating healthcare, whether scheduling and attending appointments, dealing with insurance companies, or worrying about the health of themselves or others. What may be surprising to find is that medicine is a major concern of a variety of non-human animals as well. Research has suggested that insects, often seen as “simpler” animals, seek out ways to treat parasites or other infections. As pointed to in a NPR article, different insects show a variety of self-medicating behaviors: wooly bear caterpillars eat plants that are toxic to parasites, wood ants use antimicrobial resin in nests, and fruit flies use fermenting fruit to protect from parasitic wasps. Many of these observations have focused on how animals use plants or other found objects in their environment to protect themselves. However, some social species also work together to help others who are too injured to help themselves.

Monarch butterflies utilize the anti-parasitic properties of milkweed to prevent infection

This type of medical care has most recently been seen in research that suggests that African Matabele ants tend to the wounds of injured ants. Although ants are not often thought of as the most complex of animals, studies have shown that together as a colony some species can complete exceptionally complicated tasks like cultivating fungus, farming aphids, or forming colonies stretching hundreds of miles. Researchers reported that African Matabele ants injured by termites were carried back to the nest by other ants, and were treated by having their wounds groomed. This species of ants specialize in hunting termites, an activity that has a high risk of injury from termite soldiers defending their nest. Researchers tested whether grooming behavior in ants was an effective treatment by either leaving ants with two limbs removed alone, or returning them back to their nest. Ants that were left “untreated” had an eighty percent 80% mortality rate, while those that were returned to the nest had 10% mortality rate. From these results, they further suggest that this grooming might prevent infections or help seal the wound. In addition, observations of ants injured in the field suggested that colonies conduct a triage-like system, in which ants that were too injured to survive the trip back to the nest were left on the battlefield, while the care of less injured ants was prioritized.

Matabele ants will carry injured ants back to the nest and effectively treat them

Yet, Matabele ants are not the only social insect that has been found to use grooming to treat fellow colony members. Over the last few decades, honey bees populations have been reduced due to parasitic mites that attack individual bees and can destroy entire hives. However, certain bees can fight off these parasites through specific grooming behaviors that damage and kill these mites. Colonies resistant to these mites have a wide variety of complex behaviors to remove these parasites, not only removing mites by grooming themselves, but also performing “grooming dances” to recruit other bees to help them.

Honey bees use grooming to remove parasitic mites, such as the two attached to a bee’s abdomen in the center of this image

Such behaviors of assessing injuries and treating other individuals adds to the list of species besides humans that care for others or help the injured. The idea that social insects have complex individual and colony behaviors used to help treat members of the colony is an interesting finding. Further, the fact that both these treatments, of injuries in Matabele ants and removing parasites in honey bees, involve grooming, shows how such behavior can be adapted to different purposes in different species. As demonstrated by these two responses to injury or illness, social species, whether ants and bees or human beings, are only successful through caring for one another.

References

Erik, Frank T., Marten Wehrhahn, and K. Eduard Linsenmair. 2018. “Wound treatment and selective help in a termite-hunting ant” Proceedings of the Royal Society B: Biological Sciences 285, (February), https://doi.org/10.1098/rspb.2017.2457

Martin, Caroline, Erick Provost, Maurice Roux, Claude Bruchou, Didier Crauser, Jean‐Luc Clement, and Yves Le Conte. 2001. Resistance of the honey bee, Apis mellifera to the acarian parasite Varroa destructor: behavioural and electroantennographic data. Physiological Entomology 26, https://doi.org/10.1046/j.0307-6962.2001.00259.x

Media Credits

[1] Photo by Katja Schulz https://commons.wikimedia.org/wiki/File:Monarch_Butterfly_on_Milkweed_(28010486509).jpg       

[2] Photo by Eric T. Frank https://en.wikipedia.org/wiki/Megaponera#/media/File:Megaponera_(injured_carried).jpg

[3] Photo by Piscisgate

https://commons.wikimedia.org/wiki/File:Honeybee_varroa_16.jpg