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Female Hosts (female + hosts)
Selected AbstractsHost sex and ectoparasites choice: preference for, and higher survival on female hostsJOURNAL OF ANIMAL ECOLOGY, Issue 4 2007PHILIPPE CHRISTE Summary 1Sex differences in levels of parasite infection are a common rule in a wide range of mammals, with males usually more susceptible than females. Sex-specific exposure to parasites, e.g. mediated through distinct modes of social aggregation between and within genders, as well as negative relationships between androgen levels and immune defences are thought to play a major role in this pattern. 2Reproductive female bats live in close association within clusters at maternity roosts, whereas nonbreeding females and males generally occupy solitary roosts. Bats represent therefore an ideal model to study the consequences of sex-specific social and spatial aggregation on parasites' infection strategies. 3We first compared prevalence and parasite intensities in a host,parasite system comprising closely related species of ectoparasitic mites (Spinturnix spp.) and their hosts, five European bat species. We then compared the level of parasitism between juvenile males and females in mixed colonies of greater and lesser mouse-eared bats Myotis myotis and M. blythii. Prevalence was higher in adult females than in adult males stemming from colonial aggregations in all five studied species. Parasite intensity was significantly higher in females in three of the five species studied. No difference in prevalence and mite numbers was found between male and female juveniles in colonial roosts. 4To assess whether observed sex-biased parasitism results from differences in host exposure only, or, alternatively, from an active, selected choice made by the parasite, we performed lab experiments on short-term preferences and long-term survival of parasites on male and female Myotis daubentoni. When confronted with adult males and females, parasites preferentially selected female hosts, whereas no choice differences were observed between adult females and subadult males. Finally, we found significantly higher parasite survival on adult females compared with adult males. 5Our study shows that social and spatial aggregation favours sex-biased parasitism that could be a mere consequence of an active and adaptive parasite choice for the more profitable host. [source] Wolbachia -induced unidirectional cytoplasmic incompatibility and the stability of infection polymorphism in parapatric host populationsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2007M. FLOR Abstract Wolbachia are intracellular, maternally inherited bacteria that are widespread among arthropods and commonly induce a reproductive incompatibility between infected male and uninfected female hosts known as unidirectional cytoplasmic incompatibility (CI). If infected and uninfected populations occur parapatrically, CI acts as a post-zygotic isolation barrier. We investigate the stability of such infection polymorphisms in a mathematical model with two populations linked by migration. We determine critical migration rates below which infected and uninfected populations can coexist. Analytical solutions of the critical migration rate are presented for mainland-island models. These serve as lower estimations for a more general model with two-way migration. The critical migration rate is positive if either Wolbachia causes a fecundity reduction in infected female hosts or its transmission is incomplete, and is highest for intermediate levels of CI. We discuss our results with respect to local adaptations of the Wolbachia host, speciation, and pest control. [source] Manipulation of oviposition choice of the parasitoid wasp, Encarsia pergandiella, by the endosymbiotic bacterium CardiniumJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2007S. G. KENYON Abstract Reproductive manipulations of hosts by maternally inherited bacterial endosymbionts often result in an increase in the proportion of infected female hosts in the population. When this involves the conversion of incipient males to genetic or functional females, it presents unique difficulties for symbionts invading hosts with sex-specific reproductive behaviours, such as the autoparasitic Encarsia pergandiella. In sexual forms of this species, female eggs are laid in whitefly nymphs and male eggs are laid in conspecific or heterospecific parasitoids developing within the whitefly cuticle. Further, eggs laid in the ,wrong' host do not ordinarily complete development. This study explored the role of a bacterial symbiont, Cardinium, in manipulating oviposition behaviour in a thelytokous population of E. pergandiella. Oviposition choice was measured by the number and location of eggs deposited by both infected and uninfected adult waSPS in arenas containing equal numbers of hosts suitable for the development of male and female waSPS. Uninfected waSPS included antibiotic-treated female waSPS and (untreated) daughters of antibiotic-treated female waSPS. The choices of waSPS in the thelytokous population treatments were compared with those of a conspecific sexual population. We found that offspring of antibiotic-cured thelytokous waSPS reverted to the behaviour of unmated sexual waSPS, laying their few eggs almost exclusively in hosts appropriate for male eggs. Infected thelytokous waSPS distributed their eggs approximately evenly between host types, much like mated sexual female waSPS. The antibiotic-treated female waSPS exhibited choices intermediate to waSPS in the other two treatments. The change in the observed behaviour appears sufficient to allow invasion and persistence of Cardinium in sexual populations. Lastly, our results suggest a reduction in host discrimination as a possible mechanism by which Cardinium influences this change. [source] Molecular Characterization of Gregarines from Sand Flies (Diptera: Psychodidae) and Description of Psychodiella n. g. (Apicomplexa: Gregarinida)THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2009JAN VOTÝPKA ABSTRACT. Sand fly and mosquito gregarines have been lumped for a long time in the single genus Ascogregarina and on the basis of their morphological characters and the lack of merogony been placed into the eugregarine family Lecudinidae. Phylogenetic analyses performed in this study clearly demonstrated paraphyly of the current genus Ascogregarina and revealed disparate phylogenetic positions of gregarines parasitizing mosquitoes and gregarines retrieved from sand flies. Therefore, we reclassified the genus Ascogregarina and created a new genus Psychodiella to accommodate gregarines from sand flies. The genus Psychodiella is distinguished from all other related gregarine genera by the characteristic localization of oocysts in accessory glands of female hosts, distinctive nucleotide sequences of the small subunit rDNA, and host specificity to flies belonging to the subfamily Phlebotominae. The genus comprises three described species: the type species for the new genus,Psychodiella chagasi (Adler and Mayrink 1961) n. comb., Psychodiella mackiei (Shortt and Swaminath 1927) n. comb., and Psychodiella saraviae (Ostrovska, Warburg, and Montoya-Lerma 1990) n. comb. Its creation is additionally supported by sequencing data from other gregarine species originating from the sand fly Phlebotomus sergenti. In the evolutionary context, both genera of gregarines from mosquitoes (Ascogregarina) and sand flies (Psychodiella) have a close relationship to neogregarines; the genera represent clades distinct from the other previously sequenced gregarines. [source] | ||||||||||