Integumental lesions caused by ectoparasites in a wild population of the side-blotched lizard (Uta stansburiana)

Histopathological effects of ectoparasites on integument were examined for a wild population of the side-blotched lizard Uta stansburiana. These included the trombiculid Neotrombicula californica, the pterygosomatid mite Geckobiella texana; the macronyssid mite Ophionyssus natricis (Macronyssidae) and the ixodid tick Ixodes pacificus. A diffuse inflammatory response occurred at the site of chigger and tick attachment which consisted of histiocyte, heterophil, fibroblast and lymphocyte infiltration that often extended into the dermis. Granuloma formation also was noted. The most prevalent parasite was N. californica which frequently occurred in large aggregations above the eyelids. Ectoparasites were most abundant from February through April.     

Schellackia occidentalis n.sp., a Blood-inhabiting Coccidian Found in Lizards in Southern California

SUMMARY. Schellackia occidentalis n. sp., is described from the following lizards from southern California: Sceloporus occidentalis becki, S. o. biseriatus , and Uta stansburiana hesperis. Evidence is presented to show that lizards become infected by ingestion of the lizard mite Geckobiella texana. The mite acts as a passive vector by swallowing infected erythrocytes. After ingestion of the mites carrying parasitized red cells, the lizard is infected by migration of the sporozoites into the lizard's intestinal epithelial cells. Schizogony and sporogony occur in the intestinal wall of the lizard. Sporozoites appear in the peripheral blood from 30 to 45 days after ingestion of infected mites. This is the first species of the genus Schellackia to be described in the Western Hemisphere.     

Detection of a malaria parasite (Plasmodium mexicanum) in ectoparasites (mites and ticks), and possible significance for transmission

Two species of sandflies (Lutzomyia) are competent vectors of Plasmodium mexicanum, a malaria parasite of lizards. The very patchy distribution of sites with high P. mexicanum prevalence in the lizards, and often low or even nil sandfly density at such sites, provoked an evaluation of 2 common lizard ectoparasites, the tick Ixodes pacificus and the mite Geckobiella occidentalis, as potential passive vectors. Plasmodium sp.-specific polymerase chain primers were used to amplify a long segment of the mitochondrial cytochrome b gene that is unlikely to survive intact if the parasite cells are killed within a blood-feeding arthropod. The segment was strongly amplified from sandflies (the positive control for the method) from 1 to 96 hr postfeeding on an infected lizard. For ticks, the gene fragment was poorly amplified at 0 hr postfeed, and not amplified after 2 hr. In contrast, strong amplification of the parasite DNA was observed from mites from 0 to 20 hr postfeed, and weak amplification even at 96 hr.     

New taxa of Kalyptorhynchia (Platyhelminthes) from the N. American Pacific coast

From the N. American Pacific coast the following new kalyptorhynchian taxa are described: Cicerinabicirrata, Cicerina triangularis, Placorhynchus pacificus, Uncinorhynchus pacificus, Proschizorhynchella lingulata, Proschizorhynchella inflata, Proschizorhynchella schilkei, Schizochilus hoxholdi, Paraschizorhynchoides glandulis Schilke subsp. hopkinsi, Cheliplana californica and Cheliplana elkhornica . The taxonomy of the species is discusscd and supplementary remarks arc made on some species from other areas.     

Species of Borrelia distinguished by restriction site polymorphisms in 16S rRNA genes

Abstract Three phyletic groups of Borrelia associated with Lyme disease, B. burgdorferi, B. garinii and group VS461 can be distinguished from each other and other species of Borrelia by Bfa I restriction site polymorphisms in PCR amplified 16S rRNA genes. One strain isolated from an Ixodes pacificus tick in California that was previously unclassifiable was distinguishable from B. burgdorferi by an Mnl I restriction site polymorphism.     

Clinical, epidemiologic, and environmental surveillance for ehrlichiosis and anaplasmosis in an endemic area of northern California.

Two forms of tick-borne leukocytotropic rickettsioses have been recognized in California since the mid-1990s: human monocytic ehrlichiosis (HME) caused by Ehrlichia chaffeensis and human granulocytic anaplasmosis (HGA) caused by Anaplasma phagocytophilum. Between 1997 and 1999, two cases of HME and four cases of HGA were diagnosed in residents of southern Humboldt County, California. Environmental followup at case-patients' residences revealed dense populations of Ixodes pacificus ticks, particularly in grassy roadside areas. PCR evidence of A. phagocytophilum was detected in approximately 2.0% of I. pacificus; E. chaffeensis was not detected in any of 625 ticks tested. Serologic antibody to A. phagocytophilum was detected in two of 54 participants in a community epidemiologic study; one of these also had antibody to E. chaffeensis. Over 85% of study participants reported finding a tick on themselves in the preceding 12 mo. Residents of southern Humboldt County are at significant risk of tick bites and should take appropriate prevention measures to avoid infection with rickettsia and other tick-transmitted pathogens.     

Origin(s), evolution,and systematics ofCucurbita pepo (Cucurbitaceae)

Numerical studies of morphological data and starch gel electrophoresis have provided a new perspective on important issues pertinent to the origin(s) and subsequent evolution of domesticatedCucurbita pepo. Wild C.texana and/orC. fraterna appear to be the most likely candidates for progenitor(s) of the domesticate. Populations of texana-like plants from beyond Texas share various attributes with Texas populations, suggesting that C. texana once had a more widespread distribution to the northeast. The possibility exists thatC. pepo was domesticated independently in eastern U.S., as well as in Mexico, which is in line with recent archeological findings. Multiple domestications are also supported by allozyme data indicating a substantial divergence within the species. A new classification consisting of C.pepo ssp.pepo (origins in Mexico),C. pepo ssp.ovifera var. ovifera (origins in eastern U.S.), and C.pepo ssp.ovifera var. texana (spontaneous populations in eastern U.S.) is proposed.     

Refractoriness of the western fence lizard (Sceloporus occidentalis) to the Lyme disease group spirochete Borrelia bissettii

The western fence lizard, Sceloporus occidentalis, is refractory to experimental infection with Borrelia burgdorferi sensu stricto, one of several Lyme disease spirochetes pathogenic for humans. Another member of the Lyme disease spirochete complex, Borrelia bissettii, is distributed widely throughout North America and a similar, if not identical, spirochete has been implicated as a human pathogen in southern Europe. To determine the susceptibility of S. occidentalis to B. bissettii, 6 na?ve lizards were exposed to the feeding activities of Ixodes pacificus nymphs experimentally infected with this spirochete. None of the lizards developed spirochetemias detectable by polymerase chain reaction for up to 8 wk post-tick feeding, infected nymphs apparently lost their B. bissettii infections within 1-2 wk after engorgement, and xenodiagnostic L. pacificus larvae that co-fed alongside infected nymphs did not acquire and maintain spirochetes. In contrast, 3 of 4 na?ve deer mice (Peromyscus maniculatus) exposed similarly to feeding by 1 or more B. bissettii-infected nymphs developed patent infections within 4 wk. These and previous findings suggest that the complement system of S. occidentalis typically destroys B. burgdorferi sensu lato spirochetes present in tissues of attached and feeding I. pacificus nymphs, thereby potentially reducing the probability of transmission of these bacteria to humans or other animals by the resultant adult ticks.     

Vertebrate hosts of Ixodes pacificus (Acari: Ixodidae) in California.

The western black-legged tick, Ixodes pacificus Cooley & Kohls, is an important parasite and vector of disease agents that affect human and animal health in the western United States. This paper presents a review of all published California host records for I. pacificus. Unpublished data from public health, academic, and vector control agencies and researchers were reviewed as well. Host species were identified for each active life stage (larvae, nymph and adult). A total of 108 vertebrate species in three classes (Mammalia, Aves, and Reptilia) were identified as hosts for at least one life stage of I. pacificus. Adult I. pacificus were recorded from 29 species of mammals, 2 species of birds, and 1 reptile species. Nymphal I. pacificus were recorded from 30 species of mammals, 38 species of birds, and 8 reptile species. Larval I. pacificus were recorded from 29 species of mammals, 43 species of birds, and 8 species of reptiles. A table depicting the taxonomic classification of host species is provided. This review adds eight new host records to the California list of recognized vertebrate host species for I. pacificus.     

The New Zealand white rabbit: an experimental host for infecting ticks with Lyme disease spirochetes

Efficiency of the New Zealand white rabbit as a host for infecting larval Ixodes dammini, I. pacificus, and I. ricinus with Lyme disease spirochetes was evaluated. Rabbits inoculated with infected midgut suspensions of I. dammini from Shelter Island, New York, or fed upon by infected ticks from the same area, responded with spirochetemias of sufficient concentrations to infect as many as 30 percent of the ticks. When infected ticks were used as indicators, it appeared that spirochetemias persisting for up to ten days occurred as early as the tenth day after inoculation or feeding of ticks.     

Pacific sleeper shark Somniosus pacificus trophic ecology in the eastern North Pacific Ocean inferred from nitrogen and carbon stable-isotope ratios and diet

Stable-isotope ratios of nitrogen (δ1?N) and lipid-normalized carbon (δ13C') were used to examine geographic and ontogenetic variability in the trophic ecology of a high latitude benthopelagic elasmobranch, the Pacific sleeper shark Somniosus pacificus. Mean muscle tissue δ13C' values of S. pacificus differed significantly among geographic regions of the eastern North Pacific Ocean. Linear models identified significant ontogenetic and geographic variability in muscle tissue δ1?N values of S. pacificus. The trophic position of S. pacificus in the eastern North Pacific Ocean estimated here from previously published stomach-content data (4·3) was within the range of S. pacificus trophic position predicted from a linear model of S. pacificus muscle tissue δ1?N (3·3-5·7) for fish of the same mean total length (L(T) ; 201·5 cm), but uncertainty in predicted trophic position was very high (95% prediction intervals ranged from 2·9 to 6·4). The relative trophic position of S. pacificus determined here from a literature review of δ1?N by taxa in the eastern North Pacific Ocean was also lower than would be expected based on stomach-content data alone when compared to fishes, squid and filter feeding whales. Stable-isotope analysis revealed wider variability in the feeding ecology of S. pacificus in the eastern North Pacific Ocean than shown by diet data alone, and expanded previous conclusions drawn from analyses of stomach-content data to regional and temporal scales meaningful for fisheries management.     

Characterization and taxonomic status of tick spiroplasmas: a review

Three serologically distinct groups of spiroplasmas have been recovered from ticks. Spiroplasma mirum strains (from rabbit ticks, Haemaphysalis leporispalustris) and Y32 group (VI) spiroplasmas (from Ixodes pacificus) are the only spiroplasmas to have a clear association with these arthropods. Group (VI) spiroplasmas are distinguished by an unusual nonhelical morphology and their capacity to hemadsorb guinea pig erythrocytes. S. mirum strains are unique in their ability to induce cataracts or lethal brain infections in a number of young vertebrates and in their virulence for the chick embryo. The 277F spiroplasma, while initially recovered from a pool of rabbit ticks (H. leporispalustris), is related by certain serological and genetic properties to spiroplasmas in the S. citri complex (serogroup I). These relationships suggest that the 277F spiroplasma may not be a natural inhabitant of the rabbit tick.     

Migratory songbirds disperse ticks across Canada, and first isolation of the Lyme disease spirochete, Borrelia burgdorferi, from the avian tick, Ixodes auritulus

During a 3-yr comprehensive study, 196 ixodid ticks (9 species) were collected from 89 passerine birds (32 species) from 25 localities across Canada to determine the distribution of avian-associated tick species and endogenous Lyme disease spirochetes, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt, and Brenner. We report the following first records of tick parasitism on avian hosts: the rabbit-associated tick, Ixodes dentatus Marx, from Manitoba and Ontario; the mouse tick, Ixodes muris Bishopp and Smith, from British Columbia; and the blacklegged tick, Ixodes scapularis Say, from New Brunswick. Moreover, we provide the first record of the Neotropical tick, Amblyomma humerale Koch (1 nymph), in Canada and its parasitism of any bird. This tick was compared morphologically with nymphs of other Neotropical Amblyomma spp., and genetically, using a 344-bp fragment of the 12S rDNA sequence of 41 New World Amblyomma species. The first collections of the western blacklegged tick, Ixodes pacificus Cooley and Kohls, from passerine species in Alberta and British Columbia, are also reported. Notably, we further report the first isolation of B. burgdorferi from the bird tick, Ixodes auritulus Neumann, collected from an American robin, Turdus migratorius L., on Vancouver Island. Furthermore, B. burgdorferi-positive I. auritulus larvae were collected from a reservoir-competent fox sparrow, Passerella iliaca (Merrem). Our findings indicate that ground-dwelling passerines, in particular, are parasitized by certain ixodid ticks and play an important role across Canada in the wide dispersal of B. burgdorferi-infected ticks and increased risk of Lyme disease exposure.     

DNA Sequence Variation at the Period Locus Reveals the History of Species and Speciation Events in the Drosophila Virilis Group

The virilis phylad of the Drosophila virilis group consists of five closely related taxa: D. virilis, D. lummei, D. novamexicana, D. americana americana and D. americana texana. DNA sequences from a 2.1-kb pair portion of the period locus were generated in four to eight individuals from each of the five taxa. We found evidence of recombination and high levels of variation within species. We found no evidence of recent natural selection. Surprisingly there was no evidence of divergence between D. a. americana and D. a. texana, and they collectively appear to have had a large historical effective population size. The ranges of these two taxa overlap in a large hybrid zone that has been delineated in the eastern U.S. on the basis of the geographic pattern of a chromosomal fusion. Also surprisingly, D. novamexicana appears to consist of two distinct groups each with low population size and no gene flow between them.     

Discovery of the Lyme disease spirochete and its relation to tick vectors.

The various hypotheses concerning the etiologic agent of erythema chronicum migrans of Europe and of Lyme disease in the United States are reviewed, and an account of events that led to the discovery of the causative spirochetal agent in Ixodes dammini is presented. Spirochetes morphologically and antigenically similar, if not identical to, the organism detected in I. dammini were also found for the first time in Ixodes pacificus and Ixodes ricinus, the vectors hitherto incriminated, respectively, in western United States and Europe. In most infected ticks, spirochetal development was found to be limited to the midgut. Ticks with generalized infections were shown to transmit spirochetes via eggs, but infections decreased in intensity and became restricted to the central ganglion as filial ticks developed to adults. Although the mechanisms of transmission to a host are still under investigation, the spirochetes may be transmitted by saliva of ticks with generalized infectious and possibly also by regurgitation of infected gut contents, or even by means of infected fecal material.     

Additional observations to the biology of Hepatozoon erhardovae Krampitz 1964 in bank voles from the south-western Styria and from areas around the Neusiedlersee (Burgenland) (author's transl)]

The incidence of Hepatozoon erhardovae in the blood of bank voles (Clethrionomys glareolus) captured in the investigated areas is examined. The biology of schizonts, their distribution in the lobes of the lung and the further development of natural infections in vertebrate hosts kept strictly free of ectoparasites are observed. The accumulation of gametocytes in larvae of the tick Ixodes ricinus and of the mite Neotrombicula zachvatkini after sucking on strongly infected bank voles is pointed out. Occasionally a parasitaemia is produced in the non-specific host (Apodemus flavicollis), but only with a specific transmitter (Megabothris turbidus).     

Ectoparasites of the island fox on Santa Cruz Island

The ectoparasite fauna for island foxes (Urocyon littoralis) on Santa Cruz Island (California, USA) in April (wet season) and September (dry season) 1998 was evaluated. Three taxa of ectoparasites were identified. These were fleas (Pulex irritans), lice (Neotrichodectes mephitidis), and ticks (Ixodes pacificus). Ectoparasite abundances varied seasonally. Typical of insular endemic species, island foxes may be especially vulnerable to the introduction of novel disease organisms and their vectors.     

Isolation of Borrelia burgdorferi from Peromyscus leucopus in Oklahoma.

Borrelia burgdorferi was isolated from a field-caught Peromyscus leucopus from central Oklahoma (USA). The strain was identified as B. burgdorferi by reaction with monoclonal antibody H5332 specific for the outer surface protein OspA of B. burgdorferi. This represents the first isolation of B. burgdorferi from a wild mouse outside of the normal range of the known vectors Ixodes dammini and I. pacificus.     

Isolation of mutations with dumpy-like phenotypes and of collagen genes in the nematode Pristionchus pacificus

The nematode Pristionchus pacificus was developed as a satellite system in evolutionary developmental biology and forward and reverse genetic approaches allow a detailed comparison of various developmental processes between P. pacificus and Caenorhabditis elegans. To facilitate map-based cloning in P. pacificus, a genome map was generated including a genetic linkage map of approximately 300 molecular markers and a physical map of 10,000 BAC clones. Here, we describe the isolation and characterization of more than 40 morphological mutations that can be used as genetic markers. These mutations fall into 12 Dumpy genes and one Roller gene that represent morphological markers for all six P. pacificus chromosomes. Using an in silico approach, we identified approximately 150 hits of P. pacificus collagen genes in the available EST, BAC-end, and fosmid-end sequences. However, 1:1 orthologs could only be identified for fewer than 20 collagen genes.     

The roles of birds, lizards, and rodents as hosts for the western black-legged tick Ixodes pacificus.

We compared the infestation by ixodid ticks of lizards, rodents, and birds collected simultaneously within areas representing common habitat types in Mendocino County, CA. Lizards were infested only by Ixodes pacificus Cooley and Kohls, birds by I. pacificus and Haemaphysalis leporispalustris (Packard), and rodents by I. pacificus, I. spinipalpis Hadwen and Nuttall, I. woodi Bishopp, Dermacentor occidentalis Marx, and D. variabilis (Say). Infestation by I. pacificus larvae and nymphs of lizards (Sceloporus occidentalis Baird and Girard; Elgaria spp.) and western gray squirrels (Sciurus griseus Ord) (means of 9-35 larvae and 5-6 nymphs per animal) was several times greater than for Neotoma fuscipes Baird woodrats, Peromyscus spp. mice, and birds (means of 0.9-3.5 larvae and 0-0.3 nymphs). Overall, Borrelia-refractory lizards accounted for 84% of I. pacificus larvae and 91% of nymphs collected from animals in dense woodlands. Bird species frequently utilizing tick-questing substrates such as leaf litter (guild I birds) were more heavily infested by I. pacificus subadults (5.2 larvae and 1.0 nymphs per bird) than guild IV birds with minimal perceived contact with tick-questing substrates (0.08 larvae and 0.06 nymphs per bird). Notably, guild I birds carried similar larval loads and at least 20-fold higher nymphal loads relative to woodrats and mice. Only guild IV birds carried as few I. pacificus nymphs as did these rodents. The ratios of larvae to nymphs suggest that, relative to birds, lizards, and squirrels (infested by 1.3-6.0 larvae per nymph), nocturnally active ground-dwelling rodents such as woodrats and mice are underutilized by the nymphal stage (69 to >100 larvae per nymph). The western gray squirrel and guild I-II birds (e.g., the dark-eyed junco, Junco hyemalis [L.]) were the only potential reservoirs of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt, and Brenner (the causative agent of Lyme disease in North America) that were frequently infested with both I. pacificus larvae and nymphs and commonly utilized dense woodland habitats.