The Effect of Migration Disturbances on the Reverse Tandem Runs of Temnothorax rugatulus

Temnothorax rugatulus ants are known to recruit via the use of tandem running, a typically two ant interaction in which a leader ant guides a follower ant to a particular location with the intent of teaching the follower ant the knowledge required to navigate to said location independently. In general, the purposes of tandem runs are fairly clear. There are tandem runs towards food in order to recruit gatherers, and there are tandem runs towards potential new nest sites to allow the colony to assess site quality. However, a group of tandem runs known as “reverse tandem runs” are a subject of mystery at this time. Reverse tandem runs are a type of tandem run found mainly during specific spans of Temnothorax colony migration. They typically arise during the period of migration when brood are being transported into a new nest site. The carriers of the brood, when returning to the old nest site to gather more brood, occasionally start tandem runs running backwards towards the old nest. In this study, the effect of navigational and physical obstacles encountered during migrations on the number of reverse tandem runs was tested. The hypothesis being that such a disturbance would cause an increase in reverse tandem runs as a method of overcoming the obstacle. This study was completed over the course of two experiments. This first experiment showed no indication of the ants having any trouble with the applied disturbance, and a second experiment with a larger challenge for the migrating ants was performed. The results of this second experiment showed that a migration obstacle will lead to an increase in migration time as well as an increase in the number of failed reverse tandem runs (reverse tandem runs that started but never reached the old nest). However, it was shown that the number of complete reverse tandem runs (reverse tandem runs that reached the old nest) remained the same whether the obstacle was introduced or not.