Lasius Psammophilus Seifert and Formica cinerea Mayr (Hymenoptera: Formicidae) on sand dunes: conflicts and coexistence
Lasius psammophilus Seifert and Formica cinerea Mayr can both be found on sand dunes in high densities. Sometimes they even nest in each other's immediate neighbourhood, which implies the possibility of conflicts, and the existence of mechanisms for avoiding contest competition. In such case an appropriate method is the analysis of the distribution and behaviour of foraging individuals around their colonies in the absence and in the presence of baits. The results show that the higher foraging activity of L. psammophilus with lower temperature and higher humidity as compared to F. cinerea , as well as the lack of spatial interference assures a relatively peaceful coexistence even in the case of neighbouring colonies. While L. psammophilus is characterized by fortuitousness regarding the chances of discovering food sources, F. cinerea foragers search more thoroughly around their colonies. Conflicts can arise over large food sources, which conflicts are usually won by F. cinerea. However, the more efficient recruitment system of L. psammophilus (earlier start and higher intensity), allows this species dominate at clumped food patches when the climatic conditions are favourable. The possible ways of coexistence are discussed, as well as the species' positions in the competition hierarchy.