The effect of habitat on the helminth parasites of an island population of the Polynesian rat (Rattus exulans)

Differences in helminth faunal composition, distribution and abundance were studied in three habitats on an island on which the Polynesian rat, Rattus exulans (Peale), is the only rodent present. The effects of season and of host age and sex were also included in the analysis. Habitat had a statistically significant effect on the prevalence and/or abundance of all seven parasites included in this study. Season influenced four species (Brachylaima apoplania, Capillaria sp., Heterakis spumosa and Mastophorus muris) but had little or no detectable effect on the remaining three (Capillaria hepatica, Hymenolepis diminuta and Syphacia muris) . Of the two intrinsic variables, age but not sex was found to have an effect. A comparison of the effects of each variable on parasite prevalence confirmed that habitat was the most important of the four variables. In a prior study on the influence of habitat on host population dynamics on this island, between-habitat differences were shown to include adult longevity, total population density and the seasonal availability and abundance of various food types. These factors, together with physical differences in the microhabitat and the parasite's life cycle, help to provide explanations for the observed results.     

Introduction of a Brachylaima species (Digenea: Brachylaimidae) to Australia

A Brachylaima species recorded previously from the house mouse (Mus domesticus) in South Australia is shown to use the introduced European snails Cernuella virgata and Cochlicella barbara as first intermediate hosts, and the same two species and Theba pisana as second intermediate hosts. The life cycle is typical of Brachylaima species. The parasite is capable of infecting at least two species of native Australian rodent, Rattus fuscipes and Leporillus conditor. Because of the intermediate hosts used, it is hypothesized that this trematode species has been introduced from Europe. The parasite may be conspecific with one of a number of described European species but difficulties with the literature concerning these species have required that the present form be designated only as Brachylaima sp.     

The parasites of the Polynesian rat: biogeography and origins of the New Zealand parasite fauna.

Unique aspects of the prehistory and current distribution of the Polynesian rat (Rattus exulans Peale) have been applied to the problem of determining the biogeographical origin of its parasites as found on 'exulans only' islands of New Zealand. The database consists of collated records of both endo- and ectoparasites reported from throughout this rat's geographical range. The analytical method is based on the concepts of Sprent (1969. Immunity to Parasitic Animals, pp. 14-17) and includes the formulation and testing of two hypotheses. A total of six 'heirloom' species is identified, and a further seven are classified as 'old souvenirs'. Contrary to prediction, 11 species are considered to be 'new souvenirs', acquired from other rodent species now present in New Zealand.     

Dating of divergences within the Rattus genus phylogeny using whole mitochondrial genomes

The timing and order of divergences within the genus Rattus have, to date, been quite speculative. In order to address these important issues we sequenced six new whole mitochondrial genomes from wild-caught specimens from four species, Rattus exulans, Rattus praetor, Rattus rattus and Rattus tanezumi. The only rat whole mitochondrial genomes available previously were all from Rattus norvegicus specimens. Our phylogenetic and dating analyses place the deepest divergence within Rattus at approximately 3.5 million years ago (Mya). This divergence separates the New Guinean endemic R. praetor lineage from the Asian lineages. Within the Asian/Island Southeast Asian clade R. norvegicus diverged earliest at approximately 2.9Mya. R. exulans and the ancestor of the sister species R. rattus and R. tanezumi subsequently diverged at approximately 2.2Mya, with R. rattus and R. tanezumi separating as recently as approximately 0.4Mya. Our results give both a better resolved species divergence order and diversification dates within Rattus than previous studies.     

The flea genus Sigmactenus (Siphonaptera: Leptopsyllidae): a new species from timor and new material from New Guinea and the Philippines

Both sexes of Sigmactenus timorensis n. sp. are described from Rattus tanezumi and Rattus exulans collected in West Timor, Indonesia. The true host presumably is a native murine rat such as the extant, endemic Rattus timorensis or 1 of several extinct, endemic Timorese rats. Analyses of new collections of Sigmactenus cavifrons and Sigmactenus toxopeusi from New Guinea demonstrate that these fleas show considerable morphological variation. We propose that they represent a single species with the name S. toxopeusi having priority. New collections of Sigmactenus werneri from the Philippines expand the known hosts and geographical distribution of this flea.     

Description of the life-cycle stages of Brachylaima cribbi n. sp. (Digenea: Brachylaimidae) derived from eggs recovered from human faeces in Australia

The life-cycle of Brachylaima cribbi n. sp. was established in the laboratory. Asymmetrical brachylaimid eggs, measuring 26-32 microm (29.1 microm) long and 16 -17.5 microm (16.6 microm) wide, were recovered from human faeces and fed to the helicid land snail Theba pisana as the first intermediate host. Sporocysts and cercariae were recovered from the T. pisana eight weeks after infection. The cercariae were used to infect the helicid land snails Cernuella virgata and Helix aspersa as second intermediate hosts. Metacercariae were recovered from the kidneys of these snails and used to infect mice. Adults of Brachylaima cribbi n. sp. were recovered from the small intestine of the mice. The differential features of B. cribbi n. sp. are the specificity for helicid snails as first and second intermediate hosts; characteristic ventral sucker and body cercarial chaetotaxy; and a long slender adult worm with equal size suckers in the first quarter of the worm, the ventral sucker occupying 41% of the body width, the uterus extending anterior to the ventral sucker and the vitelline follicles falling short of the posterior margin of the ventral sucker. No other known Brachylaima species exhibits all of these features. B. cribbi n. sp. is the first brachylaimid known to have infected humans and is probably of European origin, as the intermediate host snails were all introduced into Australia from Europe.     

Brachylaima succini sp. nov. (Trematoda: Brachylaimidae) from Succinea lauta,an amber snail in Hokkaido,Japan

Through a continuous survey of trematodes in land snails of Hokkaido, the northernmost island of Japan, we have discovered four species of the genus Brachylaima (Trematode: Brachylaimidae). Among them, Brachylaima ezohelicis, Brachylaima asakawai, and Brachylaima lignieuhadrae have already been described. Each of the three species is a strict specialist in selecting a particular species of land snail as the first intermediate host. In this report, we propose the fourth species, Brachylaima succini sp. nov., based on ecological, morphological, and phylogenetic considerations. Sporocysts and metacercariae of the new species were found exclusively from Succinea lauta, which is known as an amber snail indigenous to Hokkaido. Phylogenetic trees of nuclear 28S rDNA and mitochondrial cytochrome c oxidase subunit 1 (cox1) demonstrated it to be distinct from the other sympatric species. Although metacercariae of the new species possessed unique morphological characters, adult worms experimentally raised from the metacercariae were similar to those of B. ezohelicis and B. lignieuhadrae. Natural definitive hosts of the new species are unknown, but the existence of common cox1 haplotypes from far-distant localities suggests a possibility that birds are involved as the definitive hosts. Findings of amber snails coinfected with both sporocysts of the new species and Leucochloridium perturbatum also support the involvement of birds.     

The brachylaimidae (Trematoda: Digenea) of Australian native mammals and birds,including descriptions of Dasyurotrema n. g. and four new species of Brachylaima

The Brachylaimidae of Australian native animals are revised. Brachylaima dasyuri (Johnston, 1913) is redescribed from Dasyurus viverrinus, Phascogale tapoatafa and Isoodon macrourus. B. simile (Johnston, 1913) is removed from synonymy with B. dasyuri, reinstated as a valid species and redescribed from Perameles nasuta, Isoodon obesulus and Antechinus stuartii. B. antechini Peisley & Howell, 1975 is reduced to synonymy with B. simile. B. brindabellensis n. sp. is described from Rattus fuscipes. B. walterae n. sp. is described from Antechinus swainsonii and A. stuartii. B. delecta n. sp. is described from Antechinus flavipes. B. sandarsae n. sp. is described from Antechinus godmani. B. pulchellum (Johnston, 1917) is redescribed from Leucosarcia melanoleuca. An unnamed Brachylaima species is described from Isoodon macrourus. New host records are Brachylaima dasyuri from Phascogale tapoatafa and B. simile from Perameles nasuta. Dasyurotrema mascomai n. g., n. sp. is described from Antechinus swainsonii. The new genus is placed in the Panopistinae. It differs from the existing genera by having a single loop of the uterus passing anterior to the ventral sucker and the genital pore posterior to the posterior testis but still distinctly ventral. A second species of Dasyurotrema is recorded, but not described, from Antechinus stuartii. Brachylaimid metacercariae are described from Rhytida capillacea, Helicarion virens, H. mastersi and Vercularion strangei. In no case was a host species found to harbour more than one species from any brachylaimid genus at a single geographical site.     

Early post-natal growth and behavioural development in the Burmese house rat, Rattus exulans

Post-natal growth of Rattus exulans was observed in 30 litters born from wild-caught females. Detailed observations of behavioural development were made on 10 litters. The physical development of the young is described and weight and length increases analyzed. Litter size varied from two to six with a mean of 3.6 ± 0.21. Major behavioural changes correlated closely with patterns of physical development. These changes occurred at 5, 15 and 22 days, and divide the post-natal development into the neonatal (0–4 days), transitional 5–14 days), socialization (15–22 days) and juvenile periods (23 days to sexual maturity). The patterns of development in Rattus exulans were considered conservative, not specialized, which is of obvious advantage to a commensal rodent and account, in part, for the success of the species as a colonizer of islands over a vast area of the Pacific.     

Ultrastructure of Sarcocystis spp. (Protozoa: Apicomplexa) in rodents from North Sulawesi and West Java, Indonesia

Tissue cysts of the protozoan genus Sarcocystis were detected in the skeletal muscles of 16 (40%) of 40 wild rodents captured in North Sulawesi and West Java, Indonesia. Two types of cysts were found to differ in their morphological characteristics. Macroscopic and microscopic cysts bounded by thick radially-striated cyst walls were detected at both locations in a total of 13 rodents belonging to seven different species (Bunomys chrysocomus, B. fratrorum, Maxomys bartelsii, M. musschenbroekii, Paruromys dominator, Rattus xanthurus and R. exulans). The primary cyst walls contained numerous broad spatula-like protrusions and the cysts were identified as S. singaporensis Zaman and Colley, 1976. In contrast, microscopic cysts bounded by thin smooth cyst walls were detected in seven rodents belonging to three different species captured at Toraut in North Sulawesi (B. chrysocomus, B. fratrorum and P. dominator). Ultrastructural examination revealed numerous slender hair-like protrusions of their primary cyst walls. It is proposed that these cysts be named S. sulawesiensis sp. n. on the basis of their unique morphological characteristics, their intermediate host range and their limited geographic distribution. Mixed infections by both species were found in three rodent species (B. chrysocomus, B. fratrorum and P. dominator).     

Tikusnema javaense n. gen., n. sp. (Nematoda: Acuarioidea) and other nematodes from Rattus argentiventer collected in west Java, Indonesia.

Nematodes collected from the ricefield rat, Rattus argentiventer (Rodentia: Muridae), in Pusakanagara and Sukamandi, West Java, Indonesia, are reported. Tikusnema javaense n. gen., n. sp. (Nematoda:Acuariidae:Seuratiinae) is described from the small intestine. This new genus is distinguished readily from other genera of the subfamily Seuratiinae in having 4 strongly protruded cuticular leaves in the posterior cephalic portion and in having a pair of prominent cuticular ornamentations posterior to deirids. Besides T. javaense, Eucoleus bacillatus, Strongyloides ratti, Nippostrongylus brasiliensis, Syphacia muris, and Physaloptera sp. were detected.     

The parasites of the Polynesian rat within and beyond New Zealand.

A list of the ecto- and endoparasites of the Polynesian rat, Rattus exulans, from throughout its geographical range is presented here. The majority of the New Zealand populations included in this survey came from 'exulans only' islands while all but one of the non-New Zealand reports came from places where other rodent species are sympatric. This information is intended among other things to highlight gaps in our knowledge of and stimulate an interest in the parasitology of this rat.     

The Diet of Feral Cats (

Feral cats became established on Raoul Island some time between 1836 and 1872; the prey available to them included a great variety of nesting seabirds, few of which are present now, landbirds and kiore (Rattus exulans). Norway rats reached the island in 1921, providing additional prey for cats, but also another potential predator of seabirds. The diet of cats is described from guts and scats collected between 1972 and 1980. Rats are the main food, with land birds second in importance, and seabirds are now a minor item. More than 90% of the rats eaten by cats are kiore although more Norway rats than kiore are trapped. Eradicating cats from Raoul Island is feasible but because Norway rats too are important predators of birds on islands, it is likely that eradicating cats without also eradicating Norway rats will do little to restore the diversity of bird species on Raoul Island, although the densities of a few species now present might be increased.     

Ectoparasites of commensal rodents in Sulawesi Utara, Indonesia, with notes on species of medical importance

Ectoparasite records are presented for four species of commensal murid rodents (Rattus rattus palelae Miller & Hollister, R. argentiventer (Robinson & Kloss), R. exulans (Peale) and Mus musculus castaneus Waterhouse) in Sulawesi Utara, with particular reference to the potential for these arthropods to bite and transmit pathogens to humans. The flea, Xenopsylla cheopis (Rothschild), was most common on R.r. palelae and is capable of transmitting plague and other pathogens to humans although no current foci for these diseases are known in Sulawesi. Hoplopleura pacifica Ewing and Polyplax spinulosa (Burmeister) sucking lice parasitized all three Rattus species although H. pacifica was mainly associated with R. exulans and P. spinulosa with R.r. palelae. These lice do not bite humans but may be intramurid vectors of murine typhus and other zoonoses. The mites Laelaps echidnina Berlese and L. nuttalli Hirst were both collected; the latter was recorded from all four murid species, mainly R. exulans. The mite Ornithonyssus bacoti Hirst was rare. Only one chigger mite, Walchiella oudemansi (Walch), was retrieved from murids (from R. exulans) and a single Leptotrombidium deliense (Walch) chigger was taken from a human subject. Although L. deliense is a significant vector of scrub typhus, a disease known from Sulawesi, the L. deliense-R. argentiventer relationship frequently noted in the ecology of this rickettsial disease, was not evident in this survey. Other ectoparasites collected from murids were the ticks, Ixodes granulatus Supino (first record for Sulawesi), Haemaphysalis sp. and Dermacentor sp., the mites Myocoptes musculinus (Koch) and Listrophoroides cucullatus (Trouessart), acarids and a uropodid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Brachylaima lignieuhadrae n. sp. (Trematoda: Brachylaimidae) from land snails of the genus Euhadra in Japan

Land snails of the genus Euhadra (Gastropoda: Bradybaenidae) are indigenous to the Japanese Archipelago. The larvae of an unknown species, tentatively named as Brachylaima sp. B (Trematoda: Brachylaimidae), have been found from Euhadra brandtii sapporo in Hokkaido, the northernmost island of Japan. In this study, a large-scale snail survey covering a wide area of Japan was conducted to confirm the larval parasite from members of Euhadra and related genera. Sporocysts with cercariae were found only from Eu. brandtii sapporo in Hokkaido and Euhadra callizona in central Honshu at low prevalence (1.0–9.6%). The metacercariae were detected widely from 6 species of Euhadra and the related genera at high prevalence (7.1–100%). A molecular identification by DNA barcoding demonstrated almost all of the larvae to be Brachylaima sp. B. Adult worms experimentally raised from the metacercariae were morphologically most similar to Brachylaima ezohelicis in Hokkaido, but could be differentiated by the microstructure of the tegumental surface. We propose Brachylaima lignieuhadrae n. sp. for the unknown species, based on the morphology, DNA profile, host specificity, and geographic distribution. Phylogeography of the new species suggests a possibility that migratory birds serve as the definitive hosts.     

Something old,something new: do genetic studies of contemporary populations reliably represent prehistoric populations of Pacific Rattus exulans?

Through our research focusing on genetic studies of both ancient and extant commensal animals in the Pacific for addressing issues of population origins and mobility in the region, we have been able to process a large number of archaeological faunal remains that we can compare to modern samples from the same islands. These comparisons shed light on and provide specific evidence for Rattus exulans population change through time. This information may provide a model for understanding human populations in the region and will illustrate the complexities of using data obtained from modern populations to infer prehistoric relationships. Two case studies are presented here-analyses of modern and archaeological populations of R. exulans from both Chatham Island and New Zealand. These two cases provide very different pictures regarding the relationship between the archaeological and the extant populations.     

Colour preferences in North Island robins (

There is growing awareness and concern in New Zealand about native birds eating poisonous baits intended for pest species such as brushtail possums (Trichosurus vulpecula) and rats (Rattus rattus, R.,norvegicus, R. exulans). We investigated the colour preferences of North Island robins (Petroica australis) a species known to be vulnerable to poisoning. The main aims were to determine if: (1) robins had colour preferences, (2) the preferences were consistent between two separate populations and 3) the preferences were similar to those found previously in weka (Gallirallus australis), another native species. Robins in Pureora Forest Park and Te Urewera National Park were individually offered a choice between differently coloured versions of a novel food (red, yellow, brown, green, light blue and medium blue) daily, for six consecutive days. Robins showed food colour preferences pecking more at the red, yellow and green cake than the medium blue, light blue or brown cake. No difference was evident in the colour preferences of the two populations. The colour preferences of robins were similar to those reported previously with weka. Dyeing poisonous baits may be sufficient to stop a proportion of robins from eating them. Further work is needed to determine how colour preferences vary across seasons, populations and species.     

Schistosoma incognitum from Cikurai,West Java,Indonesia

Schistosoma incognitum is reported for the first time from West Java, Indonesia where 84% of ricefield rats, Rattus argentiventer, were infected. Radix auricularia rubiginosa snails were intermediate hosts. The adult stage of the Javanese strain of S. incognitum and lesions in naturally-infected rodents are described. Rattus exulans, Rattus norvegicus and Mus musculus were experimentally infected. Epizootiology is similar to that described in other countries.     

Brachylaima asakawai sp. nov. (Trematoda: Brachylaimidae), a rodent intestinal fluke in Hokkaido,Japan, with a finding of the first and second intermediate hosts

In the 1970’s and 1980’s, an unknown species of the genus Brachylaima (Trematoda: Brachylaimidae) had been recorded from the intestines of Rattus norvegicus and Apodemus speciosus in Hokkaido, Japan. The rodent fluke was characteristic in extending a bilateral vitellarium till the level of posterior margin of anterior testis and in keeping almost the same-sized spherical ovary and testes. In this study, the rodent fluke was rediscovered from A. speciosus, Apodemus argenteus, and Myodes rufocanus in Hokkaido. The resultant parasite collection enabled us to make a mitochondrial DNA (mtDNA) barcode for tracking its intermediate hosts. The metacercaria of the rodent fluke was detected frequently from the kidney of three species of land snails (Discus pauper, Succinea lauta, and Ainohelix editha). However, its sporocyst with cercariae was found only from the hepatopancreas of D. pauper, a fairly small snail. The wide-spectrum of the second intermediate host seems to increase the chance of transmitting the parasite to various mammals and birds. The use of indigenous land snails as the first and second intermediate hosts, the distinctiveness of the mtDNA sequence, and the characteristic morphology of all the developmental stages prompted us to propose Brachylaima asakawai sp. nov. for the rodent intestinal fluke in Hokkaido. The present field survey suggests that the life cycle of the new species is primarily dependent on a predator-prey relationship between rodents and D. pauper.