We investigated the seasonal occurrence and vertical distribution/migration of larval and juvenile northern smoothtongue, Leuroglossus schmidti (Pisces, Bathylagidae), in oceanic areas of the western subarctic Pacific. This species was the most abundant larval fish and one of the most abundant juvenile/adult fish at the study site. Larval recruitment of this species occurred in early March to mid-October. Larvae were found, however, throughout all seasons, suggesting that some had overwintered. The highest abundance (5.8 individuals m–2) of larvae was in summer. During summer and autumn, hatching mainly occurred at 100–150-m depth and larvae migrated toward the surface with growth. Once larvae reached about 20 mm in length, they moved below 100 m, and larger larvae (over 24 mm) exhibited diel vertical migration. The abundance of juveniles integrated through the water column was relatively constant (0.3 individuals m–2) throughout the study period. They were collected from below 300 m during the day, and part of the population (13–38%) swam into the epipelagic layer at night. The information on early stages of L. schmidti presented here provides a basis for future investigations of mesopelagic fish ecology in oceanic areas of the western subarctic North Pacific Ocean.

The European lantern fly Dictyophara europaea (Linnaeus, 1767), is a polyphagous dictyopharid planthopper of Auchenorrhyncha commonly found throughout the Palaearctic. Despite abundant data on its distribution range and reports on its role in the epidemiology of plant-pathogenic phytoplasmas (Flavescence dorée, FD-C), literature regarding the biology and host plants of this species is scarce. Therefore, the aims of our study were to investigate the seasonal occurrence, host plant associations, oviposition behaviour and immature stages of this widespread planthopper of economic importance. We performed a 3-year field study to observe the spatio-temporal distribution and feeding sources of D. europaea. The insects's reproductive strategy, nymphal molting and behaviour were observed under semi-field cage conditions. Measurement of the nymphal vertex length was used to determine the number of instars, and the combination of these data with body length, number of pronotal rows of sensory pits and body colour pattern enabled the discrimination of each instar. We provide data showing that D. europaea has five instars with one generation per year and that it overwinters in the egg stage. Furthermore, our study confirmed highly polyphagous feeding nature of D. europaea, for all instars and adults, as well as adult horizontal movement during the vegetation growing season to the temporarily preferred feeding plants where they aggregate during dry season. We found D. europaea adult aggregation in late summer on Clematis vitalba L. (Ranunculaceae), a reservoir plant of FD-C phytoplasma strain; however, this appears to be a consequence of forced migration due to drying of herbaceous vegetation rather than to a high preference of C. vitalba as a feeding plant. Detailed oviposition behaviour and a summary of the key discriminatory characteristics of the five instars are provided. Emphasis is placed on the economic importance of D. europaea because of its involvement in epidemiological cycles of phytoplasma-induced plant diseases.

Seasonal occurrence of metazoan ectoparasites is described for the first time in marine European flounder, Platichthys flesus (L.). The parasitofauna, in this study monitored during 1 year, was found to be similar to that previously recorded for flounder. Moreover, specimens of Caligus sp. Müller, 1785 and Lepeophtheirus pectoralis (Copepoda: Caligidae), Acanthochondria cornuta (Copepoda: Chondracanthidae), Holobomolochus confusus (Copepoda: Bomolochidae) and Nerocila orbignyi (Isopoda: Cymothoidae), and also, a praniza larva (Isopoda: Gnathiidae), were isolated. From these, L. pectoralis and A. cornuta were the dominant parasites in all samples of flounder, while Caligus sp., H. confusus, N. orbignyi and the gnathiid praniza seemed to infect the flounder only occasionally. As far as the seasonality of infections is concerned, it differed considerably from that described for estuarine environments. Indeed, both prevalence and abundance of L. pectoralis and A. cornuta reached significant peaks in the summer, whereas the literature identifies the autumn as the season of maximum infection on estuarine flounder. Thus, the former period seems more favourable for the occurrence of epizooties of L. pectoralis and A. cornuta in flounder culturing systems running on seawater and operated in the studied or similar environments.

Five myxozoan species, Tetracapsuloides bryosalmonae, Sphaerospora truttae, Chloromyxum schurovi, Chloromyxum truttae and a Myxobolus species were detected in farmed brown trout, Salmo trutta L. from Central Scotland. Using PCR and in situ hybridization, this study investigated the seasonal occurrence and tissue location of these species in young of the year brown trout. C. schurovi, C. truttae and Myxobolus sp. were first detected in brown trout in April, 2 months before T. bryosalmonae and S. truttae. T. bryosalmonae and S. truttae showed proliferation in the blood with intravascular stages of T. bryosalmonae accumulating in the heart. In contrast, only small amounts of PCR products of C. schurovi and C. truttae were obtained from the blood, suggesting that these species use the vascular system for transport but proliferate only in their target tissues from which large amounts of PCR product were obtained and where parasites were visible in histological sections. Large amounts of PCR product were obtained for T. bryosalmonae, S. truttae and both Chloromyxum species from the gills of brown trout, suggesting the gills as entry locus for these species. The neurotropic Myxobolus species formed plasmodia predominantly in the peripheral nerves, possibly indicating an entry route through the skin. Presporogonic stages of all other species had disappeared by September and mature spores were present from August onwards.

ECFXPERT is a microcomputer software tool which can be used to investigate tick populations and the control of East Coast fever. The package contains four simulation models: a model for predicting the abundance and seasonality of Rhipicephalus appendiculatus ticks; a model for predicting East Coast fever prevalence within a herd of cattle; and two models for the study of disease control using either acaricidal dipping strategies or chemotherapy. In this paper, the philosophy of the ECFXPERT package, and the underlying assumptions and mathematical techniques employed are presented, along with the results of a number of computer experiments designed to validate and illustrate potential use of the model.