Composition and transstadial retention of the salivary glands in Ornithodoros hermsi (Acari: Argasidae)

Following several days of blood feeding by larval and nymphal ixodid (hard) ticks, the salivary glands degenerate and are completely replaced in the next life stage. Yet, what happens during the molt of immature argasid (soft) ticks after their rapid and small bloodmeal has remained a mystery. Multiple studies of nymphal Ornithodoros hermsi Wheeler (Acari: Argasidae) ticks infected with the relapsing fever spirochete Borrelia hermsii suggested the salivary glands in these ticks may not disintegrate after feeding. Therefore, cohorts of second-stage O. hermsi nymphs were fed and examined daily after the bloodmeal by fresh dissections and weekly by histological cross-sections of the entire tick. The composition of the salivary glands was typical for argasid ticks in having agranular (Type I) and granular (Type II) acini, the latter being surrounded by a myo-epithelial sheath. In all 197 ticks examined from 1 to 63 days after feeding, morphologically intact salivary glands were present. During apolysis, 5 ticks had extralimital clusters of granular acini adhering to otherwise intact glands. Our observations demonstrate that the salivary glands of nymphal O. hermsi do not disintegrate after feeding and new acini are produced during the molt for incorporation into the existing glands. Cumulatively, these findings suggest a fundamental difference in the transstadial development of argasid and ixodid ticks.

Detection of Rickettsia lusitaniae Among Ornithodoros sawaii Soft Ticks Collected From Japanese Murrelet Seabird Nest Material From Gugul Island, Republic of Korea

In a follow-up to the investigations of soft ticks identified from seabird nest soil and litter collected from coastal islands of the Republic of Korea (ROK), Ornithodoros sawaii and Ornithodoros capensis were assessed for the presence and identification of rickettsiae. Ticks collected from samples of 50-100 g of nest litter and soil from seabird nests were identified individually by morphological techniques, and species confirmed by sequencing of the mt-rrs gene. Subsequently, tick DNA preparations were screened for the presence of rickettsiae using a genus-specific nested PCR (nPCR) assay targeting the 17 kDa antigen gene. The amplicons from the 17 kDa assay and two additional nPCR assays targeting the gltA and ompB gene fragments were sequenced and used to identify the rickettsiae. A total of 134 soft ticks belonging to two species, O. sawaii Kitaoka & Suzuki 1973 (n = 125) and O. capensis Neumann 1901 (n = 9), were collected. Rickettsia lusitaniae DNA was detected and identified among O. sawaii ticks (n = 11, 8.8%) collected from nest litter and soil of the Japanese murrelet (Synthliboramphus wumizusume Temminck 1836) at Gugul Island along the western coastal area of the ROK. This study confirmed for the first time the presence of R. lusitaniae associated with O. sawaii collected from migratory seabird nests in the ROK.

Soft ticks perform evaporative cooling during blood-feeding

Feeding on the blood of warm-blooded vertebrates is associated to thermal stress in haematophagous arthropods. It has been demonstrated that blood-sucking insects protect their physiological integrity either by synthesising heat-shock proteins or by means of thermoregulatory mechanisms. In this work, we describe the first thermoregulatory mechanism in a tick species, Ornithodoros rostratus. By performing real-time infrared thermography during feeding on mice we found that this acarian eliminates big amounts of fluid (urine) through their coxal glands; this fluid quickly spreads over the cuticular surface and its evaporation cools-down the body of the tick. The spread of the fluid is possible thanks to capillary diffusion through the sculptured exoskeleton of Ornithodoros. We discuss our findings in the frame of the adaptive strategies to cope with the thermal stress experienced by blood-sucking arthropods at each feeding event on warm-blooded hosts.

Ornithodoros cerradoensis n. sp. (Acari: Argasidae), a member of the Ornithodoros talaje (Guérin-Méneville, 1849) group, parasite of rodents in the Brazilian Savannah

Ornithodoros cerradoensis n. sp. is described from field-collected and laboratory reared nymphs, males, females, and larvae parasitizing the rodents Cavia aperea and Thrichomys sp. in the Brazilian Savannah. This new species is morphologically and genetically related with the Ornithodoros talaje group and can be separated from other Neotropical species using the following combination of characters: larva with 18 pairs of setae on dorsum (seven anterolateral, four central and seven posterolateral), hypostome with median dentition 2/2; adults provided with large mammillae; dorsal disks surrounded by bulked marginal ridges delimiting barely pebbled areas; three disks in the anterolateral file, and median disk not merging with the posteromedian file. Feeding assays in the laboratory demonstrated that (1) larvae of O. cerradoensis are slow-feeders (∼6 days), (2) first nymphal instar (N1) molts to second instar (N2) without feeding, and (3) N2 and third nymphal instar (N3) engorge rapidly (minutes). With the exception of Ornithodoros hasei nymphs that depict flattened bodies, O. cerradoensis N1, N2, and N3 highly resemble homologous instars of other species in O. talaje sensu lato, therefore are not suitable for morphological comparisons within the group. In addition to morphological signature of larvae and adults that separate this new species; results of cross-mating attempts between O. cerradoensis and Ornithodoros guaporensis a morphologically and phylogenetically closely related species that also parasitizes rodents in the Brazilian Savannah; a Principal Component Analysis using larval characters; and a phylogenetic analysis using mitochondrial markers, support O. cerradoensis as an independent lineage within the Ornithodorinae.

Description of a new soft tick species (Acari: Argasidae: Ornithodoros) parasite of Octodon degus (Rodentia: Octodontidae) in northern Chile

A new argasid (Argasidae) tick is herein described based on morphology and molecular data obtained from larvae parasitizing Octodon degus and from ticks collected inside burrows in northern Chile. Unfed laboratory-reared larvae were mounted in slides for morphometrical and morphological analyses. Larvae of Ornithodoros octodontus n. sp. share morphological traits with Ornithodoros quilinensis and Ornithodoros xerophylus, two species associated with rodents in the Argentinean Chaco. However, a longer hypostome with two rows of 21 and 22 denticles each one, and conspicuous leaf-shaped anal plates separate O. octodontus. While nymphal stages of O. octodontus lack cheeks and possess a micromammillated dorsal integument, adults have cheeks and exhibit markedly irregular mammillae along their dorsal surface. Phylogenetic analyses of neotropical Argasidae based on mitochondrial 16S rDNA sequences point that O. octodontus forms a monophyletic group with O. xerophylus and an unidentified Ornithodoros sp. from Bolivia, all of them associated with burrow-dweller rodents. Ornithodoros aragaoi and Ornithodoros davisi, two rare species collected once only in the Peruvian Andean Plateau during 1955 are morphologically closely related with adults and nymphs of O. octodontus. Biological observations of O. octodontus revealed autogenic females. For the moment, subgeneric classification of this new species depends on further biological studies. The fauna of ticks occurring in Chile is now represented by 22 species, 11 belonging to the Argasidae family.

Description of Ornithodoros montensis n. sp. (Acari, Ixodida: Argasidae), a parasite of the toad Rhinella arenarum (Amphibia, Anura: Bufonidae) in the Monte Desert of Argentina

A new tick species of the genus Ornithodoros (Acari: Argasidae) was described from larvae collected on the toad Rhinella arenarum in a locality from Argentina belonging to the Monte Biogeographic Province. Ornithodoros montensis n. sp. was described based on morphological traits and sequences of the mitochondrial 16S rRNA gene. The diagnostic characters for this species are a combination of idiosoma oval, dorsal plate pyriform with posterior margin slightly concave, dorsal surface with 17 pairs of setae (7 anterolateral, 4 to 5 central and 5 to 6 posterolateral), ventral surface with 6 pairs of setae and 1 pair on anal valves, three pairs of sternal setae, postcoxal setae absent, and hypostome pointed apically with dental formula 3/3 in the anterior half and 2/2 posteriorly almost to base. Phylogenetic analysis of 16S rDNA sequences and a principal component analysis based on morphometric characters provided additional support to the description of O. montensis as an independent lineage within the genus Ornithodoros. Larvae of O. montensis are phylogenetically closely related to O. puertoricensis, O. rioplatensis, O. talaje s.s., O. guaporensis, O. hasei and O. atacamensis, all of them belonging to the "O. talaje group".

Detection of Rickettsia spp. in ticks associated to wild mammals in Northeastern Brazil, with notes on an undetermined Ornithodoros sp. collected from marsupials

We report tick infestations and rickettsial detection in ticks infesting free-living wild mammals (Monodelphis domestica, Tolypeutes tricinctus, Thrichomys inermis and Kerodon rupestris) captured in the Caatinga ecoregion of Bahia state, northeastern Brazil, during September to December 2016. Overall, 117 ticks (61 larvae, 25 nymphs, 25 males, 6 females) belonging to two genera, and at least three species were collected: Amblyomma auricularium, Amblyomma parvum, Amblyomma sp., Ornithodoros rietcorreai and an unidentified Ornithodoros sp. We provide new host records to the rodent T. inermis parasitized by larva and nymphs of A. auricularium and to the marsupial M. domestica infested by larvae of A. auricularium. Furthermore, we describe new tick-host association for larvae of O. rietcorreai on the rodents K. rupestris and T. inermis. Concerning tick-Rickettsia associations, we detected Rickettsia amblyommatis and an uncharacterized species of Rickettsia belonging to the spotted fever group (SFG) in both A. auricularium and A. parvum. Additionally, 'Candidatus Rickettsia andeanae' was detected in A. parvum as well.

New records of ticks infesting bats in Brazil, with observations on the first nymphal stage of Ornithodoros hasei

In Brazil, at least 14 species of soft ticks (Argasidae) are associated with bats. While Ornithodoros hasei seems to be abundant among foliage-roosting bats, other groups of ticks are found exclusively inside caves. In this paper, noteworthy records of soft ticks infesting bats are documented in new localities from Bahia, Pernambuco, Piauí, and Rondônia states. Out of 201 bats examined, 25 were infested by 152 ticks belonging to seven taxa: Ornithodoros cavernicolous, O. hasei, Ornithodoros marinkellei, Ornithodoros cf. fonsecai, Ornithodoros cf. clarki, Antricola sp., and Nothoaspis amazoniensis. These findings provide new insights into the geographical distribution and host association of soft ticks occurring in the Neotropical region. Remarkably, morphological and biological observations about O. hasei are inferred based on the examination of on-host-collected first stage nymphs.

Identification and characterization of a histamine-binding lipocalin-like molecule from the relapsing fever tick Ornithodoros turicata

Lipocalins are low molecular weight membrane transporters that are abundantly expressed in the salivary glands and other tissues of ticks. In this study, we identified a lipocalin-like molecule, designated as otlip, from the soft ticks Ornithodoros turicata, the vector for the relapsing fever causing spirochete Borrelia turicatae. We noted that the expression of otlip was developmentally regulated, with adult ticks expressing significantly higher levels in comparison to the larvae or nymphal ticks. Expression of otlip was evident in both fed and unfed O. turicata ticks, with significantly increased expression in the salivary glands in comparison to the midgut or ovary tissues. High conservation of the biogenic amine-binding motif was evident in the deduced primary amino acid sequence of Otlip. Protein modelling of Otlip revealed conservation of most of the residues involved in binding histamine or serotonin ligand. In vitro assays demonstrated binding of recombinant Otlip with histamine. Furthermore, prediction of post-translational modifications revealed that Otlip contained phosphorylation and myristoylation sites. Taken together, our study not only provides evidence for the presence of a lipocalin-like molecule in O. turicata ticks but also suggests a role for this molecule in the salivary glands of this medically important vector.

Impact of life stage-dependent dispersal on the colonization dynamics of host patches by ticks and tick-borne infectious agents

BACKGROUND

When colonization and gene flow depend on host-mediated dispersal, a key factor affecting vector dispersal potential is the time spent on the host for the blood meal, a characteristic that can vary strongly among life history stages. Using a 2-patch vector-pathogen population model and seabird ticks as biological examples, we explore how vector colonization rates and the spread of infectious agents may be shaped by life stage-dependent dispersal. We contrast hard (Ixodidae) and soft (Argasidae) tick systems, which differ strongly in blood- feeding traits.

RESULTS

We find that vector life history characteristics (i.e. length of blood meal) and demographic constraints (Allee effects) condition the colonization potential of ticks; hard ticks, which take a single, long blood meal per life stage, should have much higher colonization rates than soft ticks, which take repeated short meals. Moreover, this dispersal potential has direct consequences for the spread of vector-borne infectious agents, in particular when transmission is transovarial.

CONCLUSIONS

These results have clear implications for predicting the dynamics of vector and disease spread in the context of large-scale environmental change. The findings highlight the need to include life-stage dispersal in models that aim to predict species and disease distributions, and provide testable predictions related to the population genetic structure of vectors and pathogens along expansion fronts.

Blood feeding of Ornithodoros turicata larvae using an artificial membrane system

An artificial membrane system was adapted to feed Ornithodoros turicata (Ixodida: Argasidae) larvae from a laboratory colony using defibrinated swine blood. Aspects related to larval feeding and moulting to the first nymphal instar were evaluated. A total of 55.6% of all larvae exposed to the artificial membrane in two experimental groups fed to repletion and 98.0% of all fed larvae moulted. Mortality rates of first instar nymphs differed significantly depending on the sorting tools used to handle engorged larvae (χ²  = 35.578, P < 0.0001): engorged larvae handled with featherweight forceps showed significantly higher mortality (odds ratio = 4.441) than those handled with a camel-hair brush. Differences in the physical properties of the forceps and camel-hair brush may affect the viability of fragile soft tick larvae even when care and the same technique are used to sort them during experimental manipulations. The current results represent those of the first study to quantify successful feeding to repletion, moulting and post-moulting mortality rates in O. turicata larvae using an artificial membrane feeding system. Applications of the artificial membrane feeding system to fill gaps in current knowledge of soft tick biology and the study of soft tick-pathogen interactions are discussed.

Molecular evidence and additional morphological characters to distinguish Ornithodoros brodyi and Ornithodoros yumatensis (Ixodida: Argasidae) in their different developmental stages

Ornithodoros brodyi and Ornithodoros yumatensis are two species distributed in the Americas and associated with bats and caves. Both species have similar morphology, and the diagnostic traits of adults have not been detailed or illustrated accurately. In this study, the independence of both species is validated on the basis of molecular evidence (using partial sequences of 16S rDNA gene), and the morphological differences between them (dentition of the hypostome and traits of individual mammillae) are confirmed through light and scanning electron microscopy. In addition to the above characteristics, we observed other traits that may serve to differentiate both species: dorsal setae are short and thick in O. yumatensis and are thin and moderate in size in O. brodyi. We also observed a conspicuous hood in O. brodyi, which was absent in O. yumatensis. Another characteristic observed is a line of setae, near the end of Tarsi II-IV, which in O. brodyi is formed by less than five setae and in O. yumatensis by more than five. The main morphological difference between larvae of the 2 species is the number of ventral setae [9 (4 circumanal pairs) in O. brodyi and 8 (3 circumanal pairs) in O. yumatensis]. The genetic divergence in 16S rDNA sequences between these two species ranges from 9.7 to 10.6%.

Ticks infesting bats (Mammalia: Chiroptera) in the Brazilian Pantanal

Ticks associated with bats have been poorly documented in the Neotropical Zoogeographical Region. In this study, a total of 1028 bats were sampled for tick infestations in the southern portion of the Brazilian Pantanal. A total of 368 ticks, morphologically identified as Ornithodoros hasei (n = 364) and O. mimon (n = 4), were collected from the following bat species: Artibeus planirostris, Platyrrhinus lineatus, Phyllostomus hastatus, Mimon crenulatum and Noctilio albiventris. Morphological identification of O. hasei was confirmed by molecular analysis. Regarding the most abundant bat species, only 40 (6.2%) out of 650 A. planirostris were infested by O. hasei, with a mean intensity of 7.2 ticks per infested bat, or a mean abundance of 0.44 ticks per sampled bat. Noteworthy, one single P. hastatus was infested by 55 O. hasei larvae, in contrast to the 2.5-7.2 range of mean intensity values for the whole study. As a complement to the present study, a total of 8 museum bat specimens (6 Noctilio albiventris and 2 N. leporinus), collected in the northern region of Pantanal, were examined for tick infestations. These bats contained 176 ticks, which were all morphologically identified as O. hasei larvae. Mean intensity of infestation was 22, with a range of 1-46 ticks per infested bat. Our results suggest that A. planirostris might play an important role in the natural life cycle of O. hasei in the Pantanal.

Experimental Infection of Ornithodoros erraticus sensu stricto with Two Portuguese African Swine Fever Virus Strains. Study of Factors Involved in the Dynamics of Infection in Ticks

African swine fever (ASF) is a frequently devastating hemorrhagic disease of domestic pigs and wild boar and Ornithodoros erraticus sensu stricto argasid ticks are the only biological vectors of African swine fever virus (ASFV) known to occur in Europe. Recently this disease emerged in Eastern Europe and Russian Federation, showing a huge potential for a rapid spread between countries. There is some risk of re-emergence of ASF in the countries where these ticks exist, that can contribute for the persistence of infection and compromise control measures. In this study we aimed to identify factors that determine the probability of infection and its dynamics in the tick vector Ornithodoros erraticus sensu stricto, with two Portuguese strains of ASFV. Our results suggest that these ticks have a high likelihood of excreting the two haemadsorbing ASF viruses of different host origins and that, in field surveys, the analysis of adults and 5th nymphal stage can provide the best chance of detecting virus infection. The results also indicate that infection of pigs with highly virulent ASF viruses will promote higher rates of infection and a higher likelihood for virus excretion by ticks. Nevertheless, there is also a risk, although lower, that ticks can become infected on pigs that have overcome the acute phase of infection, which was simulated in our study by membrane feeding ticks with low titres of virus. We believe these results can be valuable in designing and interpreting the results of ASF control programmes, and future work can also be undertaken as our dataset is released under open access, to perform studies in risk assessment for ASFV persistence in a region where O. erraticus sensu stricto ticks are present.

Distribution of endemic and introduced tick species in Free State Province, South Africa

The distributions of endemic tick vector species as well as the presence of species not endemic to Free State Province, South Africa, were determined during surveys or opportunistic collections from livestock, wildlife and vegetation. Amongst endemic ticks, the presence of Rhipicephalus appendiculatus was confirmed in the north of the province, whilst Rhipicephalus decoloratus was collected at 31 localities mostly in the centre and east, and Ixodes rubicundus at 11 localities in the south, south-west and centre of the province. Amongst the non-endemic species adult Amblyomma hebraeum were collected from white rhinoceroses (Ceratotherium simum) on four privately owned farms, whilst the adults of Rhipicephalus microplus were collected from cattle and a larva from vegetation at four localities in the east of the province. The collection of Rhipicephalus evertsi mimeticus from a sheep in the west of the province is the second record of its presence in the Free State, whereas the presence of Haemaphysalis silacea on helmeted guineafowl (Numida meleagris) and vegetation in the centre of the province represents a first record for this species in the Free State. The first collection of the argasid tick, Ornithodoros savignyi, in the Free State was made from a domestic cow and from soil in the west of the province. The localities at which the ticks were collected have been plotted and the ticks' role in the transmission or cause of disease in domestic livestock and wildlife is discussed.

Two new species of Ornithodoros (Ixodida; Argasidae) from the Southern Cone of South America

Two new species of the genus Ornithodoros were described from larvae collected in Argentina and Chile. Ornithodoros xerophylus n. sp. was described from specimens collected on the small rodent Graomys centralis in Argentina. The diagnostic characters for this species are a combination of dorsal plate slightly oval with a length of approximately 250 µm, 16 pairs of dorsal setae, hypostome with apex rounded and dental formula 2/2 in most rows, 3/3 apically, and capsule of the Haller's organ oval in shape without reticulations. Larvae of Ornithodoros lahillei n. sp. were collected on the reptiles Philodryas chamissonis and Callopistes maculatus in Chile. The diagnostic characters for O. lahillei are a combination of dorsal plate subtriangular with margins corrugated and posterior margin convex, dorsal surface with 14 pairs of setae, absence of postcoxal setae, and hypostome with apex pointed and dental formula 3/3 in anterior third and 2/2 in the middle and basal portion. Phylogenetic analysis of 16S rDNA sequences and a Principal Component Analysis based on morphometric characters provided additional support to the description of O. lahillei and O. xerophylus as two independent lineages within the genus Ornithodoros.

Life cycle of Ornithodoros rostratus (Acari: Argasidae) ticks feeding on mice under laboratory conditions

Ornithodoros rostratus Aragão is an argasid tick found in Bolivia, Paraguay, Argentina and Brazil. Only limited studies about O. rostratus have been conducted and several aspects of their life cycle differ among studies or remain unexplored. In order to better elucidate the biology of O. rostratus, the present work describes its life cycle when feeding on mice under laboratory conditions. To complete their life cycle on mice, O. rostratus goes through a larval stage, 3-6 nymphal instars (nymph 1-6) and adult male and female. Adults can be originated from nymph 3-6. Nymphs 4 with higher weight after feeding tend to originate adults. Adults originated from early instars tended to be lighter. Females tended to be heavier than males. Larvae needed on average 2.7 days to complete their blood meal whereas other instars ranged from 17.3 to 78.3 min. The capacity to ingest blood was higher in larvae and females in comparison to males. The preecdysis period ranged from 5 to 12.5 days. After one blood meal, females remain on average 15.2 ± 5.8 days laying 276.8 ± 137.2.9 eggs. Females originated from nymph 4 had similar oviposition time, egg incubation and conversion ingested blood/number of eggs produced, but presented lower initial weigh and weigh gain, generating fewer eggs. Our results added novel information on O. rostratus biology and was discussed considering the variability of argasid populations and in context with the differences about their life cycle described in previous works.

Cell lines from the soft tick Ornithodoros moubata

Primary cell cultures (n = 16) were initiated from tissues of embryonic and neonatal larval Ornithodoros moubata following methods developed for hard ticks. After maintenance for 20-25 months in vitro, cell multiplication commenced in surviving cultures, leading to the establishment of six cell lines designated OME/CTVM21, 22, 24, 25, 26 and 27. All lines are maintained at 28 degrees C, with subculture at 2-8 week intervals. The cultures comprise heterogeneous populations of large cells of 15-100 microm in diameter, often with finger-like protrusions and/or intracellular crystals, rarely attached, predominantly floating and forming clumps or hollow multicellular vesicles up to 1 mm in diameter. Attempts to cryopreserve the cells are described. Tick-borne encephalitis virus has been serially passaged ten times in OME/CTVM21 cells without significant decrease in virus production and with no change in its biological properties as shown by the size and morphology of plaques produced in porcine kidney cells.

Isolation and expression of the retinoid X receptor from last instar nymphs and adult females of the soft tick Ornithodoros moubata (Acari: Argasidae)

Retinoid X receptors (RXR) exist broadly from invertebrates to vertebrates, and play essential roles in physiological processes of these organisms. In arthropods, RXRs form a complex with the ecdysteroid receptor (EcR) and ecdysteroids to mediate the regulation of ecdysis and reproduction. Compared to EcR, RXR and its homologue ultraspiracle (USP) are much less well understood. Therefore, we identified RXR of the soft tick Ornithodoros moubata (OmRXR) and used real-time PCR to examine the expression of OmRXR. This is the first report of RXR from a soft tick. OmRXR showed higher homology to hard tick, crustacean and vertebrate RXRs than insect RXRs and USPs. OmRXR expression was observed during molting in the last instar nymphs coinciding with EcR expression and increases in ecdysteroid titers. Tick vitellogenesis normally occurs soon after engorgement and OmRXR expression coinciding with EcR expression and ecdysteroid titers in engorged females occurred before vitellogenin (Vg) synthesis and egg maturation. The ecdysteroid/EcR/RXR complex appears to be important in the regulation of molting and vitellogenesis of soft ticks.

Effects produced by the feeding of larvae of Ornithodoros aff. puertoricensis (Acari: Argasidae) on laboratory mice

The clinical picture produced by the feeding of larvae of Ornithodoros aff. puertoricensis on laboratory mice, was studied using different larval infestation protocols that included 30, 40 or 50 larvae per mouse and control uninfested groups. Clinical effects appeared around 72 h of larval feeding, having a first stage characterized by hyperaemia in both nasal and ocular mucosa, followed by respiratory symptoms (96-120 h) and nervous incoordination (120-144 h). No one mouse evidenced paralysis, and nervous symptoms were never observed in animals infested with only 30 larvae. High mortality (commonly up to 70%) was observed in mice with respiratory symptoms, while 100% of animals in the nervous phase died between 168 and 192 h after the beginning of larval feeding. When some infested mice were treated with a solution of Amitraz the larvae were killed and reversion of symptoms was observed. These effects are ascribed to the presence of a toxin in the saliva of the feeding larvae.

Ferruginous Pygmy-Owl (Glaucidium brasilianum) and Eastern Screech-Owl (Megascopes asio): New Hosts for Philornis mimicola (Diptera: Muscidae) and Ornithodoros concanensis (Acari: Argasidae)

While banding ferruginous pygmy-owls (Glaucidium brasilianum) and Eastern screech-owls (Megascops asio) in south Texas during 2004, we recorded Philornis mimicola (Diptera: Muscidae) and Ornithodoros concanensis (Acari: Argasidae) parasitizing nestlings. Inspection of nestlings revealed 54 P. mimicola and one O. concanensis. Inspection of nest material revealed 111 P. mimicola, including 57 puparia. The effect (e.g., blood loss, anemia) of these hematophagous parasites might have contributed to the demise of at least one Eastern screech-owl nestling. This is the first record of P. mimicola and O. concanensis parasitizing ferruginous pygmy-owls and Eastern screech-owls.

Kinetics of African swine fever virus infection in Ornithodoros erraticus ticks

The kinetics of African swine fever virus (ASFV) infection in Ornithodoros erraticus ticks were investigated in specimens collected in the field at different times following an outbreak of the disease in Portugal in 1999 and in ticks infected experimentally with a virus isolated from a tick collected during this outbreak. In ticks collected from the field, initial screening for ASFV was carried out by PCR, followed by attempts to isolate the virus in macrophage cultures. Considering total numbers of ticks tested independently of developmental stages, ASFV DNA was detected in 42.3, 26.4 and 22.4% of specimens collected at weeks 0, 32 and 63 following the outbreak, respectively. Although virus was not isolated from most of these ticks, the proportion of isolations from large nymphs and adults increased between weeks 0 and 32 from 2 to 9 % and from 5 to 11.5%, respectively. These results, together with the higher virus titres at week 32, suggest that virus replication occurred. In contrast, virus isolations from small nymphs decreased over this period, from 5 to 1.3%. At week 63, infection rates decreased for all stages. Experimental infections showed the occurrence of virus replication within 4 weeks post-feeding and maintenance of high titres in almost 100% of ticks until 20 weeks post-infection. At weeks 41 and 61, a drop in virus titres and infection rates was observed. Relevant to the understanding of African swine fever epidemiology, our results show that ASFV replicates and persists in O. erraticus, but a viral clearance occurs at later times in both natural and experimental infections.

Morphological and populational characteristics of hemocytes of Ornithodoros moubata nymphs during the ecdysial phase

The ultrastructure and characteristics of hemocytes of argasid tick species, Ornithodoros moubata, during the ecdysdial phase are herein presented. Hemocyte classes/populations characterized based on their affinity with Giemsa stain and ultrastructural differences comprised the prohemocytes, nongranular cells (Nc), eosinophilic granular cells (Ec), basophilic granular cells (Bc), and unidentified cells. Significant changes/shift in the ratio of hemocyte classes/population was apparent in ticks before and after the ecdysial phase. The granule-scant basophilic granular cells (sBc) constituted the most abundant hemocyte population in the ecdysial phase. Nymphs in ecdysis showed increases in Nc and sBc and decrease in Ec, a phenomenon that was reversed in unengorged nymphs and adults ticks. The significant increase in total Bc population in ecdysis relative to nonengorged ticks clearly point to blastogenesis of Bc taking place during the ecdysial phase and Bc's important role in the process of tissue remodeling.

Ectoparasite associations of bats from central Pennsylvania

Between April and October 1997, 689 bats representing seven species were captured at Pennsylvania's Canoe Creek State Park. Each bat was sampled for ectoparasitic arthropods, and four species were collected from 13.2% of the host individuals. Ectoparasites include the bat flea Myodopsylla insignis (Rothschild), the wing mite Spinturnix americanus (Banks), the bed bug Cimex adjunctus Barber, and the soft tick Ornithodoros kelleyi Cooley & Kohls. Prevalence, relative density, and mean intensity were calculated for ectoparasites of Myotis lucifugus (Le Conte), which harbored all four ectoparasite species and was the most commonly captured host. Patterns of ectoparasite associations were examined with respect to host sex and habitat (roost characteristics). Female M. lucifugus hosted higher densities of ectoparasites than did males. Moreover, relative densities of ectoparasites from M. lucifugus were dependent on the proximate roost; hosts captured near Bat Church were more heavily parasitized than those captured near Hartman Mine. Two other bat species were infested with at least one ectoparasite, but sample sizes were too small to analyze statistically. These bat species included Myotis septentrionalis (Trouessart), harboring M. insignis, S. americanus, and O. kelleyi, and Eptesicus fuscus (Beauvois), which harbored M. insignis and O. kelleyi.

Existence of phenol oxidase in the argasid tick Ornithodoros moubata

Phenol oxidase (PO, EC 1.10.3.1) activity was detected in the hemolymph of the fourth instar nymphs of the argasid tick, Ornithodoros moubata, with peak levels corresponding to the days before the majority of the nymphs had molted, suggestive of a protective role of PO during the ecdysial phase. Higher PO activity was detected in plasma relative to the hemolymph and was negligible in hemocytes. The concentration of the hemolymph and plasma assayed clearly influenced the level of PO activity, and was significantly reduced ( P<0.005) after treatment with 1-phenyl-2 thiourea, a specific PO inhibitor. This is the first report of the existence of PO in the hemolymph and plasma of a soft tick species. The regulation of PO activity and its precise role in soft tick immunity, particularly during the ecdysial phase, are interesting and need to be examined further.