Natures wonders: ants kill ants, disinfect nest (Introduction)

by David Turell @, Monday, April 16, 2018, 19:13 (8 days ago) @ David Turell

New research has identified the compounds that signal sickness:

"The team also noticed that workers were destroying infected pupae while the fungal infection was still in its incubation period, before it had become visible or contagious. Something other than the infectious agent was telling the workers that the ants were sick. Pull and his colleagues knew that ants communicate with their nestmates via chemical compounds called cuticular hydrocarbons (CHCs), and suspected that the infected pupae might be signaling workers in this manner.

"To test the hypothesis, the researchers washed some of the infected pupae with a solvent to remove CHCs. Presented with these pupae, the worker ants carried out their disinfection routine 72 percent less often than when they were given infected pupae that were unwashed or had been rinsed with water. The researchers then used gas chromatography to confirm that infected pupae that hadn’t been solvent treated had a unique chemical profile on their cuticles—a kind of “find-me/eat-me” signal, Pull notes, functionally similar to those released by apoptotic cells to attract phagocytic immune cells in the human body (eLife, 7:e32073, 2018).

"While this sickness cue usually leads to the death of the infected individual by stimulating disinfection behavior in workers, it protects the rest of the colony, including egg-producing queens, from fatal infection, Pull says. “[The sick ants] are performing these behaviors and putting themselves at risk, but at the end of the day it’s still to maximize genes which they carry, to ensure that genes they carry are being passed on to the next generation.”
Provided the colony’s queen survives to pass on her genes, the evolutionary fitness of every individual is maximized, explains Cremer. “In systems like this, selection acts on the level of the reproductive entity,” favoring the evolution of collective defenses or “social immunity.” The kind of altruistic chemical cues discovered by the team “could be very widespread” among social insects, Cremer adds. The CHCs that make up the “disinfect-me” signal for L. neglectus are upregulated not only in ants during fungal infection, but also in honeybees—which have similar colony dynamics—after viral infection or when injected with bits of bacterial cells, she notes."

Comment: Again, this mechanism had to be present from the beginning of nesting or insect nests would not have survived. Certainly requires design.

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