Risk aversion helps ants avoid obstacles, predators

Desert ants can recall traps or obstacles and adjust their routes accordingly. Photo by Cornelia Buehlman/CNRS
Desert ants can recall traps or obstacles and adjust their routes accordingly. Photo by Cornelia Buehlman/CNRS

April 9 (UPI) -- Ants are adept navigators, but when ants find their typical route blocked by an obstacle or predator, they're able to adjust, according to a new study.

But ants don't simply ad-lib a workaround. Research suggests they adopt and memorize a new preferred path.


Lab tests showed ants use what scientists dubbed an aversive learning mechanism. By associating visual cues with negative experiences, ants can memorize and avoid dangerous routes.

For the tests, scientists at the French National Center for Scientific Research placed a pit trap with slippery walls in the ants' path back to the nest. A tiny bridge disguised by twigs allowed the trapped ants to escape.

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At first, all of the ants bee-lined right into the trap on their way home. On the second go-around, many of the ants slowed and even stopped. The cautious ants scanned the environment and opted for an alternate route.

The tests -- described in the journal Current Biology -- showed ants recalled the visual stimuli that preceded their sudden fall and later recalled those cues.

Researchers tested two species of desert ant, Melophorus bagoti from Australia and Cataglyphis fortis from the Sahara, and observed similar results.

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"The views experienced before falling into the trap become associated with the ensuing negative outcome and thus trigger salutary turns on the subsequent trip," scientists wrote in their paper. "This drives the ants to orient away from the goal direction and avoid the trap. If the pit trap is avoided, the novel views experienced during the detour become positively reinforced and the new route crystallizes."

Scientists plan to incorporate the newly identified aversive learning mechanism into their current neural models to better understand the intricacies of the insect nervous system.

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