USE OF ANT-NEST DEBRIS BY DARKLING BEETLES AND OTHER ARTHROPOD SPECIES IN AN ARID SYSTEM IN SOUTH EUROPE

Desert ecosystems are more complex than expected and, in this type of habitat, interspecific interactions can be an important force structur ing the community. In this paper we described an interaction appearing between an harvester ant species (Messor bouvieri) and several arthro pod taxa feeding on ant-nest debris in a southern European arid land. We have found 23 arthropod taxa associated with the nests of Messor bo uvieri. During the daily period of maximum activity, the abundance of beetles inside mounds of ant-nests can be 660 times greater than the b eetle abundance on the soil surface. Five beetle species were signific antly more abundant inside the ant mounds than outside. We believe tha t four of these five species-Morica hybrida, Pimelia integra P. montic ola, and Tentyria incerta-are highly specialized in the use of ant-nes t debris as an important source of food. Finally, we think that the re maining species, Aphodius baeticus, uses the ant nests principally as an arena for mating. In conclusion, we believe that, during the hot se ason, this 'unusual' interaction could be an essential factor regulati ng the food web and trophic structure in these arid lands. (C) 1995 Ac ademic Press Limited