Carpenter ants (Camponotus), a diverse genus of large ants indigenous to many forested parts of the world, can selectively treat the wounded limbs of fellow nestmates — either by wound cleaning or amputation.
Open wounds pose major infection and mortality risks in animals. To reduce these risks, many animal species apply antimicrobial compounds on their wounds.
In 2023, researchers discovered that a different ant species, Megaponera analis, uses a special gland to inoculate injuries with antimicrobial compounds meant to quell possible infections.
What makes Florida carpenter ants (Camponotus floridanus) and other species of the genus Camponotus stand out is that because they have no such gland, they appear to be using only mechanical means to treat their nestmates.
University of Würzburg’s Dr. Erik Frank amd his colleagues found that this mechanical care involves one of two routes.
The ants would either perform wound cleaning with just their mouthparts or perform a cleaning followed by the full amputation of the leg.
To select which route they take, the ants appear to assess the type of injury to make informed adjustments on how best to treat.
In the study, two types of leg injuries were analyzed, lacerations on the femur and those on the ankle-like tibia.
All femur injuries were accompanied by initial cleaning of the cut by a nestmate, followed by a nestmate chewing off the leg entirely. In contrast, tibia injuries only received the mouth cleaning.
In both cases, intervention resulted in ants with experimentally infected wounds having a much greater survival rate.
“Femur injuries, where they always amputated the leg, had a success rate around 90% or 95%. And for the tibia, where they did not amputate, it still achieved about the survival rate of 75%,” Dr. Frank said.
“This is in contrast to the less than 40% and 15% survival rate for unattended infected femur and tibia abrasions,…
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