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Temporal and spatial distribution patterns of a population of Talitrus saltator living on the Tyrrhenian coast of Tuscany (Italy) were studied. Bimonthly surveys were performed from March 1991 to January 1992 along transects using a standard system of pitfall traps and sieves for surface-active and burrowed individuals, respectively. Captured individuals were subdivided into sex and age classes (on the basis of the number of articles of the flagellum of the second antenna). Abundances were calculated for each sampling period and sex ratios were determined. For each sampling period the mean hour of surface activity was calculated together with the mean zonation of both surface-active and burrowing sandhoppers belonging to the different sex and age classes. Shifts in mean zonation between the resting and active phase were also determined. For each category of sex, age, and reproductive phase, simple and multiple regression analyses were used to find relationships of the mean zonation of surface-active animals with climatic data, and of the number of burrowed individuals with surface sand parameters recorded in correspondence to the sieves. On the whole, the results show that this Tyrrhenian population of T. saltator exhibited a bivoltine reproductive cycle and that the sex ratios of active sandhoppers were male or female biased according to the season. The variations in the mean hour of surface activity and in the zonation patterns of sandhoppers depended more on the age than on the sex. Furthermore distribution patterns were generally related to seasonal changes in the local climatic and substrate parameters. The observed differences between burrowing and activity zonations were interpreted on the basis of the nocturnal migrations of the different categories. [ABSTRACT FROM AUTHOR]

Presents a study that examined the spatial distributions of sand beach arthropods at Zouara, a beach dune system along the northwestern coast of Tunisia. Assessment of the capture frequency of the arthropod species; Analysis of environmental parameters in the beach dune system; Differences in the seasonal distribution of the species.

Examines the timing, orientation and motivating and directing factors of the spontaneous movements of the sandhopper Talitrus saltator on a Mediterranean beach in Tuscany, Italy. Landward migration after sunset for juveniles; Effect of temperature on spontaneous movements; Description of the habitat of the sandhopper, Talitrus saltator.

The littoral sandhopper Talitrus saltator Montagu maintains its position along the beach mainly by means of an innate solar orientation. Different populations show different directional tendencies depending on the direction of the sealand axis. Experiments were designed which aimed to disentangle the innate and acquired components of the escape orientation. Therefore, the solar orientation of experienced adults living on shores subject to fluctuations of the shoreline and of their laboratory-born (inexperienced) offspring were compared. The innate sun compass orientation shown by the young is modified by learning during life under natural conditions, depending on the variability of the shore. Results showed: (1) an improvement in the solar orientation in individuals living on relatively constant shores; (2) a loss of precision in individuals living on highly dynamic shores; (3) a change to a new ecologically efficient escape direction in individuals living on a relatively stable lagoon shore. [ABSTRACT FROM AUTHOR]

Three natural populations of Talitrus saltator living on differently orientated seashores and the offspring produced by crossing two of them were analysed by means of progeny tests, with the aim of gaining some data on the genetic control of solar direction finding. Data from fullsib family-analyses showed a genetic heterogeneity within at least two of the populations tested: some families oriented towards the sea, some in a different direction and others were dispersed. Intrafamily behaviour in the first and second generations and a mass analysis of dispersed families, suggests that dispersion may arise from segregation of heterozygous parental genotypes. The data obtained generally support the hypothesis of an oligogenic rather than a polygenic control of direction finding. [ABSTRACT FROM AUTHOR]

The present paper reports on the first orientation experiments conducted 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 Tyrrhenian beach in Italy and the other a beach on the Atlantic coast of France. Response to sun compass cues was demonstrated in each population at the collection site and for the French population after transportation to Italy, where experiments were carried out on a differently oriented beach. Landscape cues were shown to improve the beetle's orientation capacity when these were tested together with a visible sun. Artificial landscapes were also tested under laboratory conditions. Different-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 angle of 25°. The results obtained for the two populations are compared and discussed from an eco-ethological point of view. [ABSTRACT FROM AUTHOR]

Two mass-crossings between individuals Talitrus saltator from populations differing in theorical escape direction (TED) were made (Fig. 1). In sun orientation tests, the F offspring of two Tyrrhenian populations differing 125 ° in TED, placed in the sun for the first time, headed in an intermediate direction between the TEDs of the parents (Fig. 3). In another crossing the F offspring of two populations differing 174 ° in TED (a Tyrrhenian and an Adriatic population) showed random orientation (Fig. 4, bottom). Hypotheses are given on the mechanism of genetic control which could explain both the initial results from crossings and specific aspects of the inherited behavioural trait (circularity, continuity, variability in space and time). [ABSTRACT FROM AUTHOR]