DIVISION-OF-LABOR IN A CRISIS - TASK ALLOCATION DURING COLONY EMIGRATION IN THE ANT LEPTOTHORAX-UNIFASCIATUS (LATR)

Division of labour during colony emigration is widespread in ants. An important problem is how tasks are allocated during colony movement fr om one nest site to another. The generally favoured view is that emigr ations are organised by a minority group of individuals, which either work unusually hard at tasks (''elites'') or have the exclusive task o f carrying out the emigration (moving specialists). Five consecutive e migrations of a Leptothorax unifasciatus (Latr.) colony showed that th e number of transporters, i.e. the individuals that took an active par t in the emigration by transporting brood and ants, was smaller than i t would have been if allocation of this task was random during each em igration. However, single emigrations of another three colonies, for w hich the spatial distribution and behaviour of the workers had been ob served for a week prior to the emigration, demonstrated that the trans porters did not form a homogeneous group. They differed in their spati al positions and tasks before the emigration. There was also no eviden ce that transporters worked harder or less hard than their nestmates b efore the emigration. Therefore, the individuals which carry out emigr ations in L. unifasciatus colonies appear to be neither moving special ists nor ''elites''. We propose that task allocation during emigration s of L. unifasciatus colonies is based on a feedback mechanism that in volves learning.