Instinct Versus Learning in the Development of a Species-Specific Caterpillar-Ant Symbiosis
Ants of the genus Iridomyrmex have symbiotic relationships with butterflies from the genus Jalmenus. In particular the ant I. anceps and butterfly J. evagoras have a symbiotic relationship that is well studied. Although the relationship itself has been investigated, the mechanism.the initiation of relationship is still unknown. To determine whether I. anceps tend J. evagoras instinctively or if the behavior is associatively learned through a reward system, the behavior of naive ants toward J. evagoras larvae post introduction was observed and recorded over 3 separate observation periods of 0, 2, and 24 h. As well as I. anceps, three other species from the subfamily Dolichoderinae, two hailing from genus Iridomyrmex, were also used in order to determine whether or not these ants, which do not normally tend J. evagoras in the field, would respond similarly or differently than I. anceps in the experimental setting. To assess changes in behavior specific aggressive and tending component behaviors were designated. During observations these particular behaviors were quantified in terms of duration and frequency and then compared within and among ant species in order to draw conclusions. There were no significant changes in the duration or frequency of the component behaviors of the non-attendant ants toward J. evagoras. This resulted in the indication that neither associative reward learning nor instinctive tendencies were present. However, the common tending ant I. anceps was found to decrease significantly in aggression overtime toward J. evagoras while exhibiting a significant increase in the frequency of a tending behavior without accessing or receiving a food reward. These changes denote that the tending behavior of I. anceps was not due to associative reward learning and was most likely linked to instinct in some manner.