Sex differences in flea infections among rodent hosts: is there a male bias?

Recognizing patterns of parasite distribution among wildlife hosts is of major importance due to growing risk of transmission of zoonotic diseases to humans. Thus, sex-dependent parasite distribution in higher vertebrates is extensively studied, and males are often found more parasit- ized than females. Male-biased parasitism may be the result of weaker immunocompetence of male hosts owing to the im- munosuppressive effect of androgens. Moreover, larger hosts (males) may demonstrate higher parasite infestation levels than smaller individuals (females), as they constitute a better nutritional resource for parasites and provide them with a greater variety of niches. In the present work, we investigated sex-dependent patterns of flea distribution among three com- mon rodent species (Apodemus agrarius, Apodemus flavicollis, and Myodes glareolus). We hypothesized that males have a higher flea infestation than females. We confirm male-biased parasitism in A. agrarius and M. glareolus, but not in A. flavicollis. Additionally, flea infestation increased with body mass in A. agrarius, but not in A. flavicollis and M. glareolus. The detected differences in parasite distribution among sexes are probably the result of immunosuppressive effects of androgens and spatial behavior of males.The research was supported by the Science and Technology Foundation (Portuguese Ministry of Science, Technology and Higher Education), grant no. SFRH/BD/ 31602/2006 and the budget of the Department of Systematic Zoology (Faculty of Biology AMU, Poznań )Parasitology Researc

The role of olfactory communications in modification of intra-specific aggression in the common hamster Cricetus cricetus (L.)

Wydział BiologiiAgresja jest zachowaniem częściej obserwowanym u gryzoni podczas eksperymentów laboratoryjnych niż w warunkach naturalnych. Uważa się, że komunikacja zapachowa może wpływać na zmniejszanie liczby agresywnych interakcji poprzez ostrzegawczo-odstraszające działanie na osobniki w populacji. W celu zbadania roli komunikacji zapachowej w zmniejszaniu liczby agresywnych interakcji, przeprowadzono serię eksperymentów na dziko żyjących populacjach chomika europejskiego w miejscowościach Jaworzno (2012-2013) oraz Przybyszów (2014-2015). W eksperymentach przeprowadzonych w warunkach naturalnych zastosowano zmodyfikowane metody Owadowskiej (1999) natomiast w warunkach seminaturalnych zmodifikowany labirynt Y (Ferkin i Seamon 1987).Wykazano, że zapach nie jest dla chomika wabiącym atraktantem, a także bodźcem odstraszającym, niezależnie od płci dawców zapachu/badanego osobnika, czy niezależnie od prawdopodobnej znajomości zapachowej osobników. Stwierdzono również, że rezydenci zamieszkujący dany obszar rzadko reagują na zapach znakowaniem czy stresem. Eksperyment z labiryntem nie wykazał, aby agresywne interakcje dominowały nad zachowaniami defensywno-stresowymi, oraz aby doświadczenia nabyte w labiryncie wpływały na późniejsze unikanie/ignorowanie zapachu osobnika, prezentowanego przy wejściu do ramion labiryntu. Wyniki badań sugerują, że zapach nie pełni funkcji odstraszającej, lecz informacyjną, pozwalającą chomikom oszacować swoje szanse oraz kondycję konkurenta w razie późniejszego bezpośredniego spotkania.Aggression is a behaviour observed more often during laboratory experiments than in nature. It is believed that scent communication might reduce the number of aggressive interactions by its warning and deterring effect. To investigate the role of chemical communication in reducing the number of aggressive interactions, a series of experiments were conducted on wild-living populations of the common hamster in Jaworzno (2012-2013) and Przybyszów (2014-2015). Modified methods of Owadowska (1999) (for experiments in natural conditions) and Ferkin and Seamon (1987) (for experiment with Y-maze in seminatural conditions) were used. It was found that scent is not an attractant, nor a deterrent for the common hamster, regardless of the sex of the scent donor/tested individual or hamsters’ familiarity. Moreover, it was concluded that the residents rarely reacted to the new scent by overmarking it or showing stress. The Y-maze experiment did not proved that aggressive interactions dominated over defensive-stress behaviour, similarly the individual’s experience from the maze did not cause avoidance or indifference to the other male’s scent from the Y-maze in the later part of the experiment. Results of the studies suggests that the role of the scent is not to deter but to inform, so hamsters can estimate their chances and rivals’ condition in case of a potential direct encounter

Differentiation of flea communities infesting small mammals across selected habitats of the Baltic coast, central lowlands, and southern mountains of Poland

Only a few studies comparing flea composition on the coast and in the mountains have been conducted. We investigated differences in flea communities infesting small mammals in selected habitats in northern, central and southern Poland. We predicted: (1) a greater number of flea species in the southeastern Poland and a lower number in the north; (2) a greater number of flea species in fertile and wet habitats than in poor and arid habitats; (3) a low similarity of flea species between flea communities in western and eastern Poland. We found negative effect of increasing latitude on flea species richness. We suppose that the mountains providing a variety of environments and the limits of the geographic ranges of several flea subspecies in southeastern Poland, result in a higher number of flea species. There was positive effect of increasing wetness of habitat on flea species richness. We found a high diversity in flea species composition between western and eastern Poland (beta diversity = 11) and between central and eastern Poland (beta diversity = 12). Re-colonization of Poland by small mammals and their ectoparasites from different (western and eastern) refugies can affect on this high diversity of flea species.grant no. SFRH/BD/ 31602/2006 from the Science and Technology Foundation (Portuguese Ministry of Science, Technology and Higher Education); budget of the Department of Systematic Zoology (Faculty of Biology AMU, Poznań)Parasitology Researc