SOLAR AND LANDSCAPE CUES AS ORIENTATION MECHANISMS IN THE BEACH-DWELLING BEETLE EURYNEBRIA-COMPLANATA (COLEOPTERA, CARABIDAE)

The present paper reports on the first orientation experiments conduct ed on the strand-living beetle Eurynebria complanata (Linnaeus, 1767) (Coleoptera, Carabidae). The experiments were carried out from June to October 1988. Two different populations were used: one inhabiting a T yrrhenian beach in Italy and the other a beach on the Atlantic coast o f France. Response to sun compass cues was demonstrated in each popula tion at the collection site and for the French population after transp ortation to Italy, where experiments were carried out on a differently oriented beach. Landscape cues were shown to improve the beetle's ori entation capacity when these were tested together with a visible sun. Artificial landscapes were also tested under laboratory conditions. Di fferent-sized silhouettes were placed in the four cardinal directions, and these envoked different responses depending on their height. The beetles oriented towards a black silhouette when this subtended an ang le of 25 degrees . The results obtained for the two populations are co mpared and discussed from an eco-ethological point of view.