Qualitative aspects of myrmecocenosis (Hym., Formicidae) in olive orchards with different agricultural management in Spain

A study has been made of the presence of ants in 60 olive trees in each of three orchards under different agricultural management in the province of Granada (southern Spain), during the months of May, July and September 1997, using both observational methods as well as the collection of specimens from the soil and trunk and the tree canopy. A total of 18 species of ants were identified, 16 of which were present in the orchard of Arenales, four in Colomera 1, and nine in Colomera 2. The number of species varies over the survey, being greatest before the flowering of the trees, this period coinciding with the lowest temperatures. The species Tapinoma nigerrimum (Nylander) was the only species present in all the samplings of the olive orchards, and the other common species in the three zones proved to be: Messor barbarus (L. 1767), Tetramorium semilaeve André and Plagiolepis pygmaea (Latr.). Most of the species found made their nests in the soil under the tree canopy, and only four species nested exclusively in open areas. Ten species foraged in the tree and seven foraged in groups. The three olive orchards were similar in phenology, temperature and humidity, and therefore the differences in the myrmecofauna at the different sites were attributed to agricultural practices at each site.