A new species of <Emphasis Type="Italic">Isospora</Emphasis> Schneider, 1881 (Apicomplexa: Eimeriidae) from the twist-necked turtle <Emphasis Type="Italic">Platemys platycephala</Emphasis> (Schneider) (Testudines: Chelidae) in Brazil

A new coccidian species of the genus Isospora Schneider 1881 (Apicomplexa, Eimeriidae) is reported from a single specimen of chelid turtle, Platemys platycephala (Schneider, 1792), obtained in a flooded area of the Amazonian municipality of Altamira, in Pará State, northern Brazil. The oöcysts of Isospora platemysi n. sp. are subspheroidal, 19.0–24.0 × 22.5–18.5 (22.6 × 20.8) µm in size [length/width ratio 1.0–1.1 (1.1)], with a colourless wall, 1.0–1.9 (1.4) wide, with two smooth layers; polar granule is present, oöcyst residuum and micropyle are both absent. The sporocyst is ovoidal, 10.0–12.1 × 8.0–10.0 (11.0 × 9.1) µm [length/width ratio 1.1–1.3 (1.2), with a knob-like Stieda body. Sub-Stieda body is present, rounded irregular-trapezoidal; para-Stieda body is absent. Sporocyst residuum is dispersed and composed of granules of differing sizes. This is only the fifth record of Isospora in chelonians, and the first report of a coccidian parasite of the genus Platemys.     

A new species of <Emphasis Type="Italic">Caryospora</Emphasis> Léger, 1904 (Apicomplexa: Eimeriidae) from the endangered Round Island boa <Emphasis Type="Italic">Casarea dussumieri</Emphasis> (Schlegel) (Serpentes: Bolyeridae) of Round Island,Mauritius: an endangered parasite?

A new species of Caryospora Léger, 1904 (Apicomplexa: Eimeriidae), C. durelli n. sp., is described from the endangered Round Island boa Casarea dussumieri (Schlegel) (Serpentes: Bolyeridae) from Round Island, Mauritius. Six of 11 hosts were infected. Oöcysts are spherical to subspherical, 19.2 × 18.2 (17.5–21 × 16–21) μm, n = 20, and have a shape index (mean length/mean width) of 1.05 (1.02–1.09). The bi-layered wall is composed of an outer layer of c.0.6 μm thick and an inner layer of c.0.4 μm thick. A micropyle, oöcyst residuum and polar granule are absent. Sporocysts are ellipsoidal, 14.7 × 11.0 (13–16 × 9.5–11.5) μm, n = 20, and have a shape index of 1.33. Both Stieda and substieda bodies are present. The sporocyst residuum measures c.12 × 4.5 μm, is surrounded by sporozoites and composed of numerous granules. Refractile bodies are present but not clearly visible. This is the first coccidian parasite reported from the family Bolyeridae and the first species of Caryospora reported from the Mascarenes. Conservation issues concerning parasites of endangered host species are discussed.     

Genetic diversity and host range of powdery mildews on Papaveraceae

Because of the strong morphological similarity of the powdery mildew fungi that infect papaveraceous hosts, a total of 39 samples were studied to reveal the phylogeny and host range of these fungi. ITS and 28S sequence analyses revealed that the isolates identified earlier as Erysiphe cruciferarum on papaveraceous hosts represent distinct lineages and differ from that of E. cruciferarum sensu stricto on brassicaceous hosts. The taxonomic status of the anamorph infecting Eschscholzia californica was revised, and therefore, a new species name, Erysiphe eschscholziae, is proposed. The taxonomic position of the Pseudoidium anamorphs infecting Glaucium flavum, Meconopsis cambrica, Papaver dubium, and Stylophorum diphyllum remain unclear. This study revealed that Erysiphe macleayae exhibits a specific host range different from that of E. cruciferarum, the common pathogen of papaveraceous hosts. Although E. macleayae occurred naturally on Macleaya cordata, Macleaya microcarpa, M. cambrica, and Chelidonium majus only, our inoculation tests revealed that the fungus was capable of infecting Argemone grandiflora, Glaucium corniculatum, Papaver rhoeas, and Papaver somniferum, indicating that these plant species may also be taken into account as potential hosts. Erysiphe cruciferarum originating from P. somniferum was not able to infect A. grandiflora, C. majus, E. californica, M. cordata, and P. rhoeas. The emergence of E. macleayae on M. microcarpa is reported here for the first time from the Czech Republic and Slovakia. The appearance of chasmothecia of E. macleayae on C. majus in Slovakia was reported, as well. Erysiphe cruciferarum was identified on G. corniculatum and reported here for the first time from Slovakia.     

To eat or not to eat infected food: a bug’s dilemma

Parasites can adversely affect host population densities, but predators can regulate disease by reducing the density of susceptible hosts and consuming parasites contained in infected hosts. Some parasites induce phenotypic modifications in their hosts that potentially lead to increased predation. We investigated the role of parasite-induced modified appearance in the interactions between the crustacean Daphnia magna, its bacterial parasite Pasteuria ramosa, and its predator, the backswimmer Anisops sp. Our aim was to test the backswimmer’s prey preference between infected and uninfected D. magna to find out whether infection by P. ramosa can affect predation risk by Anisops. We found that Anisops sp. had a strong preference for uninfected D. magna under light, but under dark conditions the preference was reversed, which suggests that the modified appearance is the cause of this preference. Such anti-parasite preference by Anisops sp. could strongly influence host population dynamics as loss of fecundity, disease mortality, and predation are additive, resulting in host population decline.     

<Emphasis Type="Italic">Isospora lopesi</Emphasis> n. sp. (Apicomplexa: Eimeriidae) from the eastern white-throated spadebill <Emphasis Type="Italic">Platyrinchus mystaceus</Emphasis> Vieillot (Passeriformes: Tyranni: Tyrannidae) in South America

A species of Isospora Schneider, 1881 (Protozoa: Apicomplexa: Eimeriidae) considered as new to science is described and characterised molecularly from the eastern white-throated spadebill Platyrinchus mystaceus Vieillot in the Parque Nacional do Itatiaia, southeastern Brazil. Isospora lopesi n. sp. has oöcysts that are subspheroidal to ovoidal, 18–24 × 18–22 (20.6 × 19.7) µm, with smooth, bilayered wall, c.1.5 μm thick. Micropyle and oöcyst residuum are absent, but one polar granule is present. Sporocysts are ellipsoidal, 12–16 × 8–11 (14.4 × 8.6) µm. The Stieda body is flattened to half-moon-shaped and sub-Stieda body is rounded. Sporocyst residuum is present, consisting of numerous spherules of different sizes. Sporozoites are vermiform with anterior and posterior refractile bodies and nucleus. Molecular analysis was conducted at the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. This new isolate exhibited similarity greater than 98% with Isospora spp. isolates from spectacled warblers Sylvia conspicillata Temminck, 1820. This is the fourth isosporoid coccidian described from New World tyrannid birds, but is the first to have a complementary molecular characterisation.     

Sex-specific effects of a parasite evolving in a female-biased host population

Background

Males and females differ in many ways and might present different opportunities and challenges to their parasites. In the same way that parasites adapt to the most common host type, they may adapt to the characteristics of the host sex they encounter most often. To explore this hypothesis, we characterized host sex-specific effects of the parasite Pasteuria ramosa, a bacterium evolving in naturally, strongly, female-biased populations of its host Daphnia magna.

Results

We show that the parasite proliferates more successfully in female hosts than in male hosts, even though males and females are genetically identical. In addition, when exposure occurred when hosts expressed a sexual dimorphism, females were more infected. In both host sexes, the parasite causes a similar reduction in longevity and leads to some level of castration. However, only in females does parasite-induced castration result in the gigantism that increases the carrying capacity for the proliferating parasite.

Conclusions

We show that mature male and female Daphnia represent different environments and reveal one parasite-induced symptom (host castration), which leads to increased carrying capacity for parasite proliferation in female but not male hosts. We propose that parasite induced host castration is a property of parasites that evolved as an adaptation to specifically exploit female hosts.

     

Parasitism (Trematoda,Digenea) in medusae from the southwestern Atlantic Ocean: medusa hosts,parasite prevalences,and ecological implications

Digenean are important endoparasites of fish with complex life cycles; some genera include medusae as secondary hosts. Their transmission to fish occurs when fish prey on these jelly hosts. Fish predation on jellyfish is a widespread phenomenon, even though predation by fish on jellyfish has not been determined through parasitism yet. We hypothesized that medusae with high prevalences of digeneans could be important for their transmission to fish. A total of 48,900 specimens of 50 medusa species were analyzed; 2,181 harbored digeneans. Opechona sp. and Monascus filiformis were the most frequent and abundant parasites with the widest range of hosts. Hemiuridae gen. sp. and Bacciger sp. were found in few specimens of some medusa species. Prevalences were unevenly distributed in the region. Three groups with high prevalence values were identified mainly related to frontal areas: Río de la Plata, Bahía Blanca, and North Patagonian tidal front. Eucheilota ventricularis, Clytia hemisphaerica, Proboscidactyla mutabilis, Liriope tetraphylla, and Aequoerea spp. were the medusae that contributed the most as secondary hosts to M. filiformis and Opechona sp. The high prevalences found in these medusae suggest that may be a fundamental part of the life cycles of both parasites in these areas.     

Coccidia of New World passerine birds (Aves: Passeriformes): a review of <Emphasis Type="Italic">Eimeria</Emphasis> Schneider, 1875 and <Emphasis Type="Italic">Isospora</Emphasis> Schneider, 1881 (Apicomplexa: Eimeriidae)

In the New World, the avian order Passeriformes comprises 47 families and 2,453 species, yet to date only 21 (45%) of the families and 58 (2%) of the species have been examined for coccidia, and from these only two species of Eimeria Schneider, 1875 and 81 species of Isospora Schneider, 1881 have been described. This review contributes to our understanding of the morphology and systematics of coccidian parasites of passeriforms, providing a scientific basis for the identification of sporulated oöcysts recovered from the faeces of passerine birds from North, Central and South America. To this end, the coccidia were organised and grouped according to the family of the host, following the widely recognised concept of family-specificity and the updated systematics of the class Aves. Details of 83 eimeriid species are presented along with an illustration and tabulated data.     

The crustacean parasites <Emphasis Type="Italic">Ellobiopsis</Emphasis> Caullery, 1910 and <Emphasis Type="Italic">Thalassomyces</Emphasis> Niezabitowski, 1913 form a monophyletic divergent clade within the Alveolata

The Ellobiopsidae are enigmatic parasites of crustaceans that have been grouped together exclusively on the basis of morphological similarities. Ultrastructural studies have revealed their affiliation within the alveolates, which was confirmed by the phylogenetic analysis of the ribosomal RNA gene (SSU rDNA) sequences of two species of Thalassomyces Niezabitowski, 1913. However, their precise systematic position within this group remains unresolved, since they could not be definitively allied with any particular alveolate group. To better determine the systematic position of ellobiopsids by molecular phylogeny, we sequenced the SSU rDNA from the type-species of the Ellobiopsidae, Ellobiopsis chattoni Caullery, 1910. We found E. chattoni infecting various copepod hosts, Acartia clausi Giesbrecht, Centropages typicus Kröyer and Clausocalanus sp., in the Bay of Marseille, NW Mediterranean Sea, which allowed us to study several stages of the parasite development. A single unicellular multinucleate specimen provided two different sequences of the SSU rDNA gene, indicating the existence of polymorphism at this locus within single individuals. Ellobiopsis Caullery, 1910 and Thalassomyces formed a very divergent and well-supported clade in phylogenetic analyses. This clade appears to be more closely related to the dinoflagellates (including the Syndiniales/Marine Alveolate Group II and the Dinokaryota) and Marine Alveolate Group I than to the other alveolates (Ciliophora, Perkinsozoa and Apicomplexa).     

A new species of <Emphasis Type="Italic">Isospora</Emphasis> Schneider, 1881 (Apicomplexa: Eimeriidae) in Ruppell’s agama <Emphasis Type="Italic">Agama rueppelli</Emphasis> (Vaillant) (Sauria: Agamidae) from East Africa,with a review of this genus in agamid lizards

Coprological examinations of eight Ruppell’s agamas Agama rueppelli (Vaillant) revealed the presence of a coccidium of the genus Isospora Schneider, 1881 that represents a previously undescribed species. Oöcysts of Isospora farahi n. sp. are spherical or subspherical, 29.1 (26–31) × 28.8 (26–31) μm, with a shape-index of 1.01 (1–1.07). An oöcyst residuum, polar granules and micropyle are absent. The oöcyst wall is bilayered, brownish and smooth, c. 1.5–2 μm thick. The sporocysts are oval, 16.6 (15–18) × 11.4 (11–12) μm, with a shape-index of 1.46 (1.25–1.64) and both Stieda and substieda bodies. A sporocyst residuum is present as medium-sized granules scattered irregularly among the sporozoites. The sporozoites are vermiform, with a large posterior spherical refractile body. Endogenous development is intranuclear in the epithelial cells of the small intestine. Sporulation is unknown, as oöcysts were recovered from the faeces.     

Spatial and genetic structure of directly-transmitted parasites reflects the distribution of their specific amphibian hosts

Parasite distributions depend on the local environment in which host infection occurs, and the surrounding landscape over which hosts move and transport their parasites. Although host and landscape effects on parasite prevalence and spatial distribution are difficult to observe directly, estimation of such relationships is necessary for understanding the spread of infections and parasite–habitat associations. Although parasite distributions are necessarily nested within host distributions, direct environmental influences on local infection or parasite effects on host dispersal could lead to distinct landscape or habitat relationships relative to their hosts. Our aim was to determine parasite spatial structure across a contiguous prairie by statistical modeling of parasite–landscape relationships combined with analysis of population genetic structure. We sampled northern leopard frogs (Lithobates pipiens) and wood frogs (L. sylvaticus) for host-specific lung nematodes (Rhabdias ranae and R. bakeri; respectively) across the Sheyenne National Grassland in southeastern North Dakota and developed primers for 13 microsatellite loci for Rhabdias. The two Rhabdias species exhibited different correlations with landscape characteristics that conformed with that of their hosts, indicating transmission is driven by host ecology, probably density, and not directly by the environment. There was evidence for localized, patchy spatial genetic structure, but no broader-scale geographic patterns, indicating no barriers to host and parasite dispersal. Nematodes cohabitating in an individual frog were most genetically similar. Worms within the same wetland were also genetically similar, indicating localized transmission and resulting wetland-scale patchiness are not completely obscured by broad-scale host–parasite dispersal. Beyond individual wetlands, we found no evidence of genetic isolation-by-distance or patchiness at the landscape-scale.     

Predation risk influences feeding rates but competition structures space use for a common Pacific parrotfish

Not all hosts, communities or environments are equally hospitable for parasites. Direct and indirect interactions between parasites and their predators, competitors and the environment can influence variability in host exposure, susceptibility and subsequent infection, and these influences may vary across spatial scales. To determine the relative influences of abiotic, biotic and host characteristics on probability of infection across both local and estuary scales, we surveyed the oyster reef-dwelling mud crab Eurypanopeus depressus and its parasite Loxothylacus panopaei, an invasive castrating rhizocephalan, in a hierarchical design across >900 km of the southeastern USA. We quantified the density of hosts, predators of the parasite and host, the host’s oyster reef habitat, and environmental variables that might affect the parasite either directly or indirectly on oyster reefs within 10 estuaries throughout this biogeographic range. Our analyses revealed that both between and within estuary-scale variation and host characteristics influenced L. panopaei prevalence. Several additional biotic and abiotic factors were positive predictors of infection, including predator abundance and the depth of water inundation over reefs at high tide. We demonstrate that in addition to host characteristics, biotic and abiotic community-level variables both serve as large-scale indicators of parasite dynamics.     

Non-native parasite enhances susceptibility of host to native predators

Parasites often alter host physiology and behavior, which can enhance predation risk for infected hosts. Higher consumption of parasitized prey can in turn lead to a less parasitized prey population (the healthy herd hypothesis). Loxothylacus panopaei is a non-native castrating barnacle parasite on the mud crab Eurypanopeus depressus along the Atlantic coast. Through prey choice mesocosm experiments and a field tethering experiment, we investigated whether the predatory crab Callinectes sapidus and other predators preferentially feed on E. depressus infected with L. panopaei. We found that C. sapidus preferentially consumed infected E. depressus 3 to 1 over visibly uninfected E. depressus in the mesocosm experiments. Similarly, infected E. depressus were consumed 1.2 to 1 over uninfected conspecifics in field tethering trials. We evaluated a mechanism behind this skewed prey choice, specifically whether L. panopaei affects E. depressus movement, making infected prey more vulnerable to predator attack. Counter to our expectations, infected E. depressus ran faster during laboratory trials than uninfected E. depressus, suggesting that quick movement may not decrease predation risk and seems instead to make the prey more vulnerable. Ultimately, the preferential consumption of L. panopaei-infected prey by C. sapidus highlights how interactions between organisms could affect where novel parasites are able to thrive.     

Avoidance of host resistance in the oviposition-site preferences of rose bitterling

A contemporary outcome of dynamic host–parasite coevolution can be driven by the adaptation of a parasite to exploit its hosts at the population and species levels (parasite specialisation) or by local host adaptations leading to greater host resistance to sympatric parasite populations (host resistance). We tested the predominance of these two scenarios using cross-infection experiments with two geographically distant populations of the rose bitterling, Rhodeus ocellatus, a fish brood parasite of freshwater mussels, and four populations of their mussel hosts (two Anodonta woodiana and two Unio douglasiae populations) with varying degrees of geographic sympatry and local coexistence. Our data support predictions for host resistance at the species level but no effect of local coexistence between specific populations. Rhodeus ocellatus showed a preference for allopatric host populations, irrespective of host species. Host mussel response, in terms of ejection of R. ocellatus eggs, was stronger in the more widespread and abundant host species (A. woodiana) and this response tended to be higher in sympatric populations. These outcomes provide support for the importance of host resistance in bitterling oviposition-site decisions, demonstrating that host choice by R. ocellatus is adaptive by minimizing egg ejections. These findings imply that R. ocellatus, and potentially other bitterling species, may benefit from exploiting novel hosts, which may not possess appropriate adaptive responses to parasitism.     

Disentangling the effects of isolation-by-distance and isolation-by-environment on genetic differentiation among <Emphasis Type="Italic">Rhododendron</Emphasis> lineages in the subgenus <Emphasis Type="Italic">Tsutsusi</Emphasis>

Ecological speciation has long been noted as a central topic in the field of evolutionary biology, and investigation into the relative importance of ecological and geographical factors is becoming increasingly emphasized. We surveyed genetic variation of 277 samples from 25 populations of nine Rhododendron species within Tsutsusi subgenus in Taiwan using simple sequence repeats of expressed sequence tags. Bayesian clustering revealed four genetic lineages: (1) the Rhododendron simsii, Rhododendron kanehirai, and Rhododendron nakaharae lineage (lineage 1); (2) the Rhododendron longiperulatum, Rhododendron breviperulatum, and Rhododendron noriakianum lineage (lineage 2); (3) the Rhododendron rubropilosum lineage (lineage 3); and (4) the Rhododendron oldhamii lineage (lineage 4). Asymmetric introgressions were found from lineage 3 into lineages 1 and 2 (introgressed lineages). Genetic admixture of non-R. oldhamii species was also revealed by a neighbor-joining tree. Variation partitioning showed that environment explained much larger portions of genetic variation than geography between non-introgressed lineages (i.e., between R. oldhamii and other lineages). However, the Mantel and partial Mantel tests and the multiple matrix regression with randomization found that isolation-by-distance played a more important role than isolation-by-environment (IBE) in contributing to genetic variation in most between lineage comparisons. Nevertheless, strong IBE was found when compared between non-introgressed lineages of R. oldhamii and R. rubropilosum, suggesting post-speciation ecological divergence. Several environmental variables, including annual mean temperature, aspect, isothermality, seasonal precipitation, slope, and soil pH, could be important ecological drivers involved in reproductive isolation between R. oldhamii and non-R. oldhamii species within the Tsutsusi subgenus.     

Helminth Diversity in Synanthropic Rodents from an Urban Ecosystem

Richness and diversity of parasites depend on a set of interrelated factors related to the characteristics of the host, the environment and the parasites itself. In the City of Buenos Aires, rodent communities vary according to landscape structure. The goal of this paper was to study the variations of helminth richness and diversity among invasive rodent species in different landscape units of the City of Buenos Aires. 73% of the rodents were parasitized with at least one of the 10 identified helminth species. Each rodent species presented its own characteristics in terms of richness, diversity and helminth composition, keeping these characteristics still occupying more than one landscape unit. The infracommunities with greater diversity corresponded to R. norvegicus due to its high values of parasitic richness, proportion of infected hosts and parasite prevalence. Instead, R. rattus and M. musculus infracommunities had lower diversity since a high percentage of them presented a unique helminth species. Within the city, the inhabitants of shantytowns would be the most exposed to zoonotic diseases transmitted by rodents due to high abundance of rodents harboring a high parasite load, including species like Hymenolepis nana and H. diminuta, recognized worldwide from a zoonotic aspect.     

Effects of Host Interspecific Interaction in the <Emphasis Type="Italic">Maculinea</Emphasis>–<Emphasis Type="Italic">Myrmica</Emphasis> Parasite–Host System

A model of interspecific host competition in a system with one parasite (butterfly—Maculinea) and multiple potential hosts (ants—Myrmica) is presented. Results indicate that host interspecific competition increases the occurrence of multiple host behaviour in Maculinea natural populations but decreases the ability of the parasite populations to adapt to the most abundant host species. These qualitative predictions were compared with data on host specificity, with good agreement. Analysis of the data also indicates that Maculinea teleius and Maculinea arion respond differently to changes in relative host abundances. Maculinea teleius shows a larger fraction of sites where it displays multiple host behaviour and a larger fraction of sites where the niches of the hosts overlap. In some instances, Maculinea teleius is adapted to Myrmica hosts that are present in lower frequencies. Maculinea arion is locally more host-specific and occurs at sites where host interspecific competition is unlikely and is more frequently adapted to the most abundant host species.     

Inactivation of proteolytic enzymes by cestodes

Inhibitor activity of cestodes from intestines of different hosts (sea birds, salt-water fish, and freshwater fish) was investigated. Alcataenia larina, Arctotaenia tetrabothrioides, Tetrabothrius erostris, T. minor, Wardium cirrosa, Bothriocephalus scorpii, Eubothrium rugosum, and Triaenophorus nodulosus were able to inhibit the activity of the commercial trypsin and activity of proteinase homogenates of the intestinal mucosa of the hosts. It was suggested that the inhibitor produced by the cestodes is specific for trypsin and protects them from the digestive enzymes of the host.     

Using Bloodmeal Analysis to Assess Disease Risk to Wildlife at the New Northern Limit of a Mosquito Species

The historically southeastern mosquito species Culex erraticus has over the last 30 years undergone a marked expansion north. We evaluated this species’ potential to participate in local disease cycles in the northeastern USA by identifying the vertebrate sources of blood in Cx. erraticus specimens from New Jersey. We found that the majority of bloodmeals (92.6%) were derived from birds, followed by 6.8% from mammals (of which half were human), and a single amphibian bloodmeal from a spring peeper (0.56%). Medium- and large-sized water birds from the order Pelecaniformes made up 60.4% of the bird species and 55.9% of all identified hosts. This group of birds is known enzootic hosts of arboviruses such as eastern equine encephalitis virus, for which Cx. erraticus is a competent vector. Additionally, we screened blooded mosquitoes for avian malaria parasites and identified three different lineages of Plasmodium, including what may represent a new Plasmodium species (likely a wetland bird specialist) in bloodmeals from Green Herons, a Great Egret, and a Double-Crested Cormorant. Our results support the utility of mosquito bloodmeals as sources of information about circulating wildlife pathogens and reveal the potential of range-expanding species to intensify local zoonoses and bridge enzootic pathogens to humans.