Collembolans and nomadism
by
Terry Mcglynn

     In a lowland wet forest in Costa Rica (La Selva), I have excavated about 40 colonies of Aphaenogaster araneoides over the past three years. Nests are in the soil, at the base of understory plants, canopy tree buttresses, and occasionally on bare ground. Nest entrances are very open, often a few cm in diameter. Nests are usually rather shallow, at most 20-30 cm deep for large colonies. About half of the colonies that I have dug up have scores of collembolans milling and hopping around at the bottom of the nest, where most of the brood are piled.
     What are they doing in there? All of the colonies of A. araneoides perform frequent nest relocation, even though home ranges do not change. After tracking relocation events prior to excavating nests, I found that nests which that contain collembolans have been occupied for longer periods of time. It appears that they might move because of them. Are they parasites? Does anyone have similar observations?