Ants prefer the option they are trained to first

Area of Science:

• Animal behavior
• Neuroethology
• Chemical ecology

Background:

• The temporal order of experiences influences memory salience in vertebrates, with a tendency to recall first and last items.
• Insect learning studies, primarily in bees, indicate a preference for the last encountered items.
• The role of recruitment pheromones in insect learning and serial position effects remains underexplored in ants.

Purpose of the Study:

• To investigate serial position learning in ants (Lasius niger).
• To determine the effect of trail pheromones on ant learning and odor preference.
• To examine how prior experience influences foraging choices.

Main Methods:

• Ants were trained on a runway with alternating lemon/rosemary odors and the presence/absence of trail pheromones.
• Preference was tested using a Y-maze to assess choices between odors.
• A familiarization visit without odor or pheromone was introduced to test preference robustness.

Main Results:

• Trail pheromone presence did not significantly affect ant choices or learning.
• Ants exhibited a strong, unexpected preference for the first odor encountered.
• A familiarization visit disrupted or reversed the first-odor preference, reverting ants to a default left-side choice.

Conclusions:

• Ants display a strong but fragile preference for the initial odor experienced, unlike bees' preference for the last item.
• Trail pheromones do not appear to modulate this specific type of learning in Lasius niger.
• This first-odor preference may influence foraging spatial segregation and colony resource exploitation.