Irrational risk aversion in an ant

Area of Science:

• Behavioral Ecology
• Neuroethology
• Decision Science

Background:

• Animals face trade-offs between safe and risky resource acquisition.
• Risk sensitivity theories explain these decisions via perceptual or fitness mechanisms.
• Eusocial insects exhibit unique collective decision-making challenges.

Purpose of the Study:

• To investigate the risk preference of individual ants (Lasius niger).
• To determine if individual ant foraging behavior predicts colony-level risk neutrality.
• To test the hypothesis that ants evaluate resources logarithmically.

Main Methods:

• Individual Lasius niger ants were trained to associate scents with different sucrose solutions.
• A Y-maze paradigm assessed preference between a safe option and a risky option (equal probability of low or high concentration).
• Further experiments manipulated the relative values of safe and risky options to test the Weber-Fechner law's applicability.

Main Results:

• 91% of individual ants exhibited extreme risk aversion, choosing the safe option.
• Results support a logarithmic basis for risk aversion in ants, aligning with the Weber-Fechner law.
• Individual ant foraging behavior was a poor predictor of previously observed colony-level risk neutrality.

Conclusions:

• Individual Lasius niger foragers are strongly risk-averse.
• Ants' risk aversion appears to stem from a logarithmic evaluation of resource value.
• Discrepancies between individual and colony behavior highlight the complexity of collective decision-making in social insects.