Uso de la encina ( Quercus ilex spp . ballota ) por la hormiga Plagiolepis pygmaea ( Hymenoptera : Formicidae ) como refugio ante medios desfavorables

The P. pygmaea (LATREILLE, 1978) species utilizes the modifications created in the environment by the holm oak tree as refuge those means which are adverse, such as the Mediterranean highly sunny pastures. However, the inner part of the vegetal covering of the tree is equally adverse, that is why this species unfolds an anular pattern, a distribution which depends on the perimeter of the tree top. Even the usage of other non-biotic resources —such as, for example, the stones— as the place of nesting, is conditioned by the distance of the tree trunk factor, so that ants prefer to build their nests under a rock, more and more often as soon as they leave it.