SPATIAL AND TEMPORAL STRATEGIES IN RELATION TO ENVIRONMENTAL CONSTRAINTS OF 4 TENEBRIONIDS INHABITING A MEDITERRANEAN COASTAL DUNE SYSTEM

The activity rhythms and zonation of four tenebrionid beetles were stu died along a transect ranging from the high eulittoral to the retrodun al area of the Burano Lagoon (Grosseto, Italy). Environmental paramete rs were registered in order to understand their correlation with surfa ce activity. For each species, population size estimates were carried out in different months by a mark-recapture method. Under laboratory c onditions activity patterns were tested at different temperatures with an aktograph apparatus and preferences for temperature and humidity o f the substrate were also analysed. The results indicate that Erodius siculus was the most thermophilic species whereas Scaurus striatus was the least. Activity rhythms varied according to the species and there was a shift from unimodal to bimodal activity as the temperature rose or as the season changed. The study indicates that different behaviou ral strategies compensate endogenous needs and enable sympatric specie s to share the same habitat through zonal partitioning and differences in the time of activity. (C) 1997 Academic Press Limited.