The aestivo-hibernation in central Greece of the aphidophagous ladybeetle Hippodamia (Semiadalia) undecimnotata (Schneider) (Coleoptera: Coccinellidae) was studied. H. undecimnotata is a multivoltine species in Greece. In the lowlands, all instars are abundant in spring, becoming scarce from July until the end of October and they are absent in winter. In June, most H. undecimnotata adults migrate to mountainous aestivo-hibernation sites. The duration of pre-oviposition period in females sampled monthly from the summits of the mountains Chlomo and Kitheron in central Greece and transferred to laboratory conditions of high temperature (25°C), long day (16L : 8D), and abundance of aphids (Aphis fabae), indicated that the H. undecimnotata females were in diapause during July and August. The diapause gradually terminated from late August to late October and was followed by a period of quiescence extending from November to March of the following year. During the summer diapause, arrested ovarian development was indicated by the undifferentiated state of the ovaries in all females. Males and females had enlarged fat bodies, and the median preoviposition period after the transfer to the laboratory was 92 days in early July and 64 days in early August. During the winter quiescence, arrested ovarian development was characterized by immature ovaries in females and, in some samples, by vitellogenic resorption in a few females. In winter, adults contained varying amounts of fat body reserves, and the median preoviposition period of females transferred to breeding conditions was 30 days in early November and 16 days in mid January.
The alimentary tract content composition of 106 European minnow (Phoxinus phoxinus, 25-75 mm TL) and 49 gudgeon (Gobio lozanoi, 31-123 mm TL) captured in August 1996 in the river Larraun (Northern Spain) was investigated in order to analyse their diet composition and interspecific diet overlap. Both species fed mainly on Chironomidae larvae, Trichoptera larvae and terrestrial invertebrates, although trophic diversity was significantly higher for European minnows. The diet composition and the feeding strategy plots revealed a similar ontogenetic shift of the relative contribution or these prey items to a more pronounced generalist feeding strategy as fish of both species grew larger. Additionally, comparisons between diet composition and the benthic macroinvertebrate community revealed that P. phoxinus and G. lozanoi refused Caenidae, showing a preference for Chironomidae and Psychomyidae. The simplified Morisita index proved that the diet overlap between the two species was indeed very high and significant. We discuss how morphological constraints - i.e. mouth size - , prey handling costs and habitat partioning could be responsible for the observed inter- and intra-specific (size-related) changes in diet preferences. However, we suggest that the combination of differential microhabitat use, diel feeding rhythms and diet plasticity could minimize the interspecific competition, allowing co-occurrence of these Cyprinidae species in relatively high densities in this reach of the river Larraun.
Knowledge of food resource partitioning between sympatric fish species is critical for understanding the fish communities functioning. Four sympatric fish species (Salmo trutta, Pseudochondrostoma duriense, Squalius carolitertii and Barbus bocagei) were captured in August 2010 in the River Tormes (Ávila, Central Spain) in order to study food resource partitioning between fish species such us as a possible mechanism enabling their coexistence, using a fuzzy principal component analysis (FPCA). Diet comparison among species shows that detritus are present in P. duriense, B. bocagei and S. carolitertii, although in different occurrence, showing that these species present typically omnivorous feeding habits. Regarding prevalent food, in all species, benthic prey constituted the most important prey in abundance terms, and terrestrial invertebrates were only consumed by S. trutta, S. carolitertii, and P. duriense. High overlap values (Schoener’s index from 0.8 up to 1) were found, but it may not indicate competition, since species can adopt different strategies to overcome competence. Thus, prey traits analyses suggest that differences in macrohabitat use, drift behaviour of prey and prey size are important adaptive features that may reduce the inter-specific competition in the fish community and permit the food partitioning that allows coexistence.
V srpnu 2017 se v Brně konala Letní škola dialogické praxe (Summer School on Dialogical Practices). Dialogické přístupy vzbuzují zájem mezi profesionály z oblasti duševního zdraví po celém světě. Letos se mezinárodní škola ve dnech 7. až 11. srpna do Brna vrátila podruhé a zde bych vám ráda dala nahlédnout do atmosféry a myšlenek účastníků, kteří přinesli své vhledy do praxe i teorie dialogických přístupů.