Analysis of Amblyomma sculptum haplotypes in an area endemic for Brazilian spotted fever

Amblyomma sculptum (Ixodida: Ixodidae) Berlese, 1888, a member of the Amblyomma cajennense complex, is the major vector of Brazilian spotted fever (BSF) in southeastern Brazil. In this study, the genetic diversity of A. sculptum populations in the state of Rio de Janeiro (RJ), Brazil, was investigated because genetic variability in tick populations may be related to vector competence. Samples of A. sculptum from 19 municipalities in 7 regions of RJ were subjected to DNA extraction, amplification and sequencing of D‐loop, cytochrome oxidase II and 12S rDNA mitochondrial genes. These sequences were used to map the genetic diversity of this tick. Amblyomma sculptum populations are genetically diverse in RJ, especially in the South Centre and Highland regions. Few unique haplotypes were observed in all populations, and the majority of genetic variation found was among ticks within each population. Phylogenetic reconstruction reinforced the assumption that all the haplotypes identified in RJ belong to A. sculptum. However, some RJ haplotypes are closer to A. sculptum from Argentina than to A. sculptum from elsewhere in Brazil. In RJ, A. sculptum has high genetic diversity, although little genetic differentiation. Observations also indicated a high level of gene flow among the studied populations and no evidence of population structure according to region in RJ.     

Ticks (Acari: Ixodidae) within various phytophysiognomies of a Cerrado reserve in Uberlandia, Minas Gerais, Brazil

Cerrado biome, the South American savannah, covers about 2 million km² and is very rich in endemic species but threatened by agriculture. In this report free-living tick species are presented, and their seasonal and relative distribution within the various phytophysiognomies in a small Cerrado reserve in Minas Gerais State, Brazil. Overall 2,694 free-living ticks were found during a 2 years sampling period with CO₂ traps and cloth dragging. Of these, 73.5% were Amblyomma cajennense and 0.6% Amblyomma dubitatum. All other ticks (25.9%) were retained as Amblyomma spp. Adults of A. cajennense peaked in spring, the nymphs in winter of both years. Amblyomma larval clusters were found in autumn and winter. Adult ticks (46.7%) and nymphs (39.5%) were most often found in woodlands, whereas most larval clusters were found in valley-side marshes (39%). Amblyomma cajennense, Anocentor nitens, Rhipicephalus (Boophilus) microplusand Rhipicephalus sanguineus ticks were found on domestic animals from neighboring properties. Search for Rickettsia in the hemolymph of 497 A. cajennense and one A. dubitatum ticks yielded negative results. Results confirmed earlier reports on the overwhelming prevalence of A. cajennense ticks in the Cerrado biome of Brazil and added information to habitat preferences of this tick species, a major vector in Brazil of the Rocky Mountain spotted fever.     

Feral pigs as hosts for Amblyomma sculptum (Acari: Ixodidae) populations in the Pantanal,Mato Grosso do Sul,Brazil

The Pantanal in Brazil is the largest floodplain of the world. This ecosystem, rich in wildlife, has a large feral pig population. Such a large host biomass must have a strong influence on the parasite fauna. In this work, we evaluated the role of feral pigs in the maintenance of Amblyomma sculptum (formerly Amblyomma cajennense), the most prevalent tick species in the Pantanal. Tick infestations were evaluated on 243 feral pigs and their environment. The suitability of domestic pigs, representing their feral relatives, to A. sculptum adults and nymphs was assessed experimentally. Tick infestation of feral pigs was strongly associated with that of the environment: 96 and 97 % of the ticks, respectively, were A. sculptum. The infestation prevalence on this host species was close to 90 % in the dry season and 100 % in the wet season and mean infestation intensity was above 30 ticks in both seasons. Suitability of pigs as hosts for A. sculptum was shown by the high proportion of nymphs and female ticks found engorging on captured feral pigs and adequate biological parameters displayed by ticks from experimental infestations of domestic pigs. Other tick species on feral pigs, albeit in much lower numbers, were Amblyomma parvum and Ornithodorus rostratus. Results show that feral pigs feed a high proportion of the A. sculptum adults and nymphs in their territories and should be a target for tick-borne diseases studies. This is particularly relevant to public health because all the main tick species found on feral pigs are aggressive to humans as well.     

Amblyomma sculptum: genetic diversity and rickettsias in the Brazilian Cerrado biome

Amblyomma sculptum (Ixodida: Ixodidae) Berlese, 1888 is the most important tick vector in Brazil, transmitting the bioagent of the most severe form of spotted fever (SF) in part of the Cerrado (in the states of Minas Gerais and São Paulo). In another part of the Cerrado (Central‐West region of Brazil), a milder form of SF has been recorded. However, neither the rickettsia nor the vector involved have been characterized. The aim of the current study was to analyse genetic variation and the presence of rickettsia in A. sculptum in Cerrado, from silent areas and with the milder form of SF. Samples were subjected to DNA extraction, amplification and sequencing of 12S rDNA, cytochrome oxidase subunit II and D‐loop mitochondrial genes (for tick population analyses), and gltA, htrA, ompA and gene D (sca4) genes for rickettsia researches. Exclusive haplotypes with low frequencies, high haplotype diversity and low nucleotide diversity, star‐shaped networks and significant results in neutrality tests indicate A. sculptum population expansions in some areas. Rickettsia amblyommatis, Candidatus Rickettsia andeanae and Rickettsia felis were detected. The A. sculptum diversity is not geographically, or biome delimited, pointing to a different potential in vector capacity, possibly associated with differing tick genetic profiles.     

Ticks (Acari: Ixodidae) in the Serra da Canastra National Park in Minas Gerais,Brazil: species,abundance, ecological and seasonal aspects with notes on rickettsial infection

The Cerrado Biome is the second largest in Brazil covering roughly 2 million km², with varying features throughout its area. The Biome is endangered but it is also source of animal species for rural, green urban and degraded rainforest areas. Ticks are among Cerrado species that establish at anthropogenic sites and although information about them is steadily increasing, several features are unknown. We herein report tick species, abundance and some ecological relationships within natural areas of the Cerrado at higher altitudes (800–1500 m) within and around Serra da Canastra National Park, in Minas Gerais State Brazil. In total of 1196 ticks were collected in the environment along 10 campaigns held in 3 years (2007–2009). Amblyomma sculptum was the most numerous species followed by Amblyomma dubitatum and Amblyomma brasiliense. Distribution of these species was very uneven and an established population of A. brasiliense in the Cerrado is reported for the first time. Other tick species (Amblyomma ovale, Amblyomma nodosum, Amblyomma parvum, Ixodes schulzei and Haemaphysalis leporispalustris) were found in lesser numbers. Domestic animals displayed tick infestations of both rural and urban origin as well as from natural areas (Rhipicephalus sanguineus sensu lato, Rhipicephalus microplus, Dermacentor nitens, A. sculptum, A. ovale, Amblyomma tigrinum, Argas miniatus). Amblyomma sculptum had the widest domestic host spectrum among all tick species. DNA of only one Rickettsia species, R. bellii, was found in an A. dubitatum tick. Several biological and ecological features of ticks of the studied areas are discussed.     

Rickettsia amblyommii infecting Amblyomma sculptum in endemic spotted fever area from southeastern Brazil

The Rickettsia bacteria include the aetiological agents for the human spotted fever (SF) disease. In the present study, a SF groupRickettsia amblyommii related bacterium was detected in a field collected Amblyomma sculptum (Amblyomma cajennense species complex) tick from a Brazilian SF endemic site in southeastern Brazil, in the municipality of Juiz de Fora, state of Minas Gerais. Genetic analysis based on genes ompA,ompB and htrA showed that the detected strain, named R. amblyommii str. JF, is related to the speciesR. amblyommii.     

Ticks (Acari: Ixodidae) of the state of Amazonas,Brazil

The tick fauna of Brazil is currently composed by 72 species. The state of Amazonas is the largest of Brazil, with an area of ≈ 19% of the Brazilian land. Besides its vast geographic area, only 19 tick species have been reported for Amazonas. Herein, lots containing ticks from the state of Amazonas were examined in three major tick collections from Brazil. A total of 5933 tick specimens were examined and recorded, comprising 2693 males, 1247 females, 1509 nymphs, and 484 larvae. These ticks were identified into the following 22 species: Amblyomma cajennense sensu lato, Amblyomma calcaratum, Amblyomma coelebs, Amblyomma dissimile, Amblyomma dubitatum, Amblyomma geayi, Amblyomma goeldii, Amblyomma humerale, Amblyomma latepunctatun, Amblyomma longirostre, Amblyomma naponense, Amblyomma oblongoguttatum, Amblyomma ovale, Amblyomma rotundatum, Amblyomma scalpturatum, Amblyomma varium, Dermacentor nitens, Haemaphysalis juxtakochi, Ixodes cf. Ixodes fuscipes, Ixodes luciae, Rhipicephalus microplus, Rhipicephalus sanguineus sensu lato. Ticks were collected from 17 (27.4%) out of the 62 municipalities that currently compose the state of Amazonas. The following four species are reported for the first time in the state of Amazonas: A. coelebs, A. dubitatum, H. juxtakochi, and Ixodes cf. I. fuscipes. The only tick species previously reported for Amazonas and not found in the present study is Amblyomma parvum. This study provides a great expansion of geographical and host records of ticks for the state of Amazonas, which is now considered to have a tick fauna composed by 23 species. It is noteworthy that we report 1391 Amblyomma nymphs that were identified to 13 different species.     

Microorganisms in the ticks Amblyomma dissimile Koch 1844 and Amblyomma rotundatum Koch 1844 collected from snakes in Brazil

Knowledge about ticks (Acari) and screening of ticks parasitizing various hosts are necessary to understand the epidemiology of tick‐borne pathogens. The objective of this study was to investigate tick infestations on snakes (Reptilia: Squamata: Serpentes) arriving at the serpentarium at the Institute Vital Brazil, Rio de Janeiro. Some of the identified ticks were individually tested for the presence of bacteria of the genera Rickettsia (Rickettsiales: Rickettsiaceae), Borrelia (Spirochaetales: Spirochaetaceae), Coxiella (Legionellales: Coxiellaceae), Bartonella (Rhizobiales: Bartonellaceae), Ehrlichia (Rickettsiales: Anaplasmataceae), Anaplasma (Rickettsiales: Anaplasmataceae), and Apicomplexa protozoa of the genera Babesia (Piroplasmida: Babesiidae) and Hepatozoon (Eucoccidiorida: Hepatozoidae). A total of 115 hard ticks (Ixodida: Ixodidae) were collected from 17 host individuals obtained from four Brazilian states. Two species of tick were identified: Amblyomma dissimile Koch 1844 (four larvae, 16 nymphs, 40 adults), and Amblyomma rotundatum Koch 1844 (12 nymphs, 43 adults). Rickettsia bellii was found in A. rotundatum and A. dissimile ticks and Rickettsia sp. strain Colombianensi, Anaplasma‐like and Hepatozoon sp. in A. dissimile ticks. Among the tested ticks, no DNA of Borrelia, Bartonella, Coxiella or Babesia was found. The present findings extend the geographic range of Rickettsia sp. strain Colombianensi in Brazil and provide novel tick–host associations.     

Capybaras and ticks in the urban areas of Uberlândia,Minas Gerais,Brazil: ecological aspects for the epidemiology of tick-borne diseases

In Brazil capybara, the biggest existing rodent species, and associated tick species, Amblyomma cajennense and Amblyomma dubitatum, are undergoing an unplanned host and parasite population expansion in both urban and rural areas. However, scientific information about such issue, particularly in urban areas, is scanty. Such rodent and ticks are associated in some municipalities, particularly in southeastern Brazil, with the transmission of the highly lethal Rickettsia rickettsia caused spotted-fever. In this study ecological aspects related to the establishment and expansion of capybaras and ticks in urban areas of Uberlandia, Minas Gerais State, Brazil were evaluated. For this purpose, capybara and tick abundance in four urban areas and an ecological reserve was determined. Abundance of capybaras varied between areas and over the sampling period and these differences were related to human activities. A positive correlation was found between capybara and tick abundance, however, the tick species had an uneven distribution within the municipality and environmental factors rather than host availability were blamed for such. On the whole these observations show that capybara populations in urban areas are associated to high environmental infestation of ticks and the increased risk of bites and of pathogen transmission to humans. At the same time the uneven distribution of tick species might implicate in an unequal risk of tick-borne diseases within the same urban area.     

Biology and life cycle of <Emphasis Type="Italic">Amblyomma incisum</Emphasis> (Acari: Ixodidae)

Amblyomma incisum Neumann is a major tick species in the Atlantic Forest of Brazil. Tapir is the main host for adult ticks and a high aggressiveness of nymphs to humans has been reported. In this work data on the biology and life cycle of this tick species is presented for the first time. It was shown that horse is a suitable host for A. incisum adults and rabbit for larvae and nymphs. It was also shown that A. incisum is a big tick species (mean engorged female weight of 1.96 g) with a long life cycle which lasts 262.3 days when maintained at 27°C and 85% RH. These laboratory conditions were, however, inappropriate and egg hatching rate (1.2%) was very low. Nevertheless egg hatching of ticks in a forest patch increased considerably (72.2%) indicating that this A. incisum population is highly dependent on a forest-like environment.     

Hosts,distribution and genetic divergence (16S rDNA) of <Emphasis Type="Italic">Amblyomma dubitatum</Emphasis> (Acari: Ixodidae)

We supply information about hosts and distribution of Amblyomma dubitatum. In addition, we carry out an analysis of genetic divergence among specimens of A. dubitatum from different localities and with respect to other Neotropical Amblyomma species, using sequences of 16S rDNA gene. Although specimens of A. dubitatum were collected on several mammal species as cattle horse, Tapirus terrestris, Mazama gouazoubira, Tayassu pecari, Sus scrofa, Cerdocyon thous, Myocastor coypus, Allouata caraya, Glossophaga soricina and man, most records of immature and adult stages of A. dubitatum were made on Hydrochoerus hydrochaeris, making this rodent the principal host for all parasitic stages of this ticks. Cricetidae rodents (Lundomys molitor, Scapteromys tumidus), opossums (Didelphis albiventris) and vizcacha (Lagostomus maximus) also were recorded as hosts for immature stages. All findings of A. dubitatum correspond to localities of Argentina, Brazil, Paraguay and Uruguay, and they were concentrated in the Biogeographical provinces of Pampa, Chaco, Cerrado, Brazilian Atlantic Forest, Parana Forest and Araucaria angustifolia Forest. The distribution of A. dubitatum is narrower than that of its principal host, therefore environmental variables rather than hosts determine the distributional ranges of this tick. The intraspecific genetic divergence among 16S rDNA sequences of A. dubitatum ticks collected in different localities from Argentina, Brazil and Uruguay was in all cases lower than 0.8%, whereas the differences with the remaining Amblyomma species included in the analysis were always bigger than 6.8%. Thus, the taxonomic status of A. dubitatum along its distribution appears to be certain at the specific level.     

Tick infestation on birds in an urban Atlantic Forest fragment in north-eastern Brazil

Birds are important hosts for various tick species, playing a significant role in their biological life cycle and dispersion. In this study, we investigated tick infestations on birds trapped in an urban remnant of Atlantic Forest in Pernambuco state, Brazil. From February 2015 to March 2017, 541 birds belonging to 52 species were trapped with mist nets and examined for ectoparasites. Birds trapped in the late successional forest were significantly more infested than birds trapped in the early successional forest. In the same way, ectoparasite infestation varied significantly according to bird weight and collection plot. Overall, 198 birds (36.6%) belonging to 27 species were parasitized by ectoparasites (i.e., ticks, lice and/or mites). Ectoparasites were effectively collected from 111 birds, of which 99 belonging to 20 species were infested by ticks (n?=?261), namely, Amblyomma longirostre (13 nymphs), Amblyomma nodosum (21 nymphs), Amblyomma varium (one nymph), and Amblyomma spp. (five nymphs and 221 larvae). Most of the ticks (>?90%) were collected from Passeriformes. This study provides the second record of A. varium in Pernambuco state and confirms that birds, especially Passeriformes, are important hosts for larvae and nymphs of Amblyomma spp. in the Atlantic Forest biome of Pernambuco.

     

Natural infestation of Hydrochoerus hydrochaeris by Amblyomma dubitatum ticks

Natural infestation of Amblyomma dubitatum in relation to individual specific attributes of Hydrochoerus hydrochaeris such as sex, body mass and body condition was analyzed. The anatomical distribution of A. dubitatum on H. hyrochaeris was also evaluated. Prevalence of adults and nymphs were significantly higher than prevalence of larvae. Non-significant differences in the infestation levels were found among host sex. Multiple regression analysis did not show any statistically significant association among the level of infestation with ticks and body mass and body condition of the host. All parasitic tick stages were collected in all five anatomical areas of the host, but they exhibited significant differences in feeding site preference. Factors associated to the host which determine the high levels of infestation with A. dubitatum could be assigned to a combination of population-level properties of the host as abundance, ubiquity and aggregation, rather than individual specific attributes related to body condition, body mass or sex.     

Microhabitat choice and its role in determining the distribution of the reptile tick Amblyomma vikirri

Abstract A newly described tick species, Amblyomma vikirri, infests two lizard species in the Flinders Ranges of South Australia. Although one of the hosts, Tiliqua rugosa, has a wide distribution, the tick distribution is restricted to a subset of rocky habitats where the other host, Egernia stokesii, lives. Experiments were conducted with unfed ticks, the stage when the tick is waiting for a host and is susceptible to desiccation. Amblyomma vikirri had a significantly stronger preference for rock microhabitats than two other tick species (Aponomma hydrosauri and Amblyomma limbatum) that infest T. rugosa. Unfed Amb. vikirri were also more active than the other two species, and more likely to be in the upper pan of the substrate. At warm temperatures, larvae of Amb. vikirri survived for shorter periods under desiccation stress than larvae of the other two species, although as nymphs Amb. vikirri survived as well or better. The rock crevice microhabitat experienced lower maximum temperatures than other potential, non-rock refuge sites. The behaviour of Amb. vikirri, its susceptibility to desiccation in the larval stage and the relatively benign conditions in the rock crevices may act together to prevent Amb. vikirri establishing populations beyond rock habitat.     

Study of the life cycle of Amblyomma dubitatum (Acari: Ixodidae) based on field and laboratory data

The life cycle of Amblyomma dubitatum was described based on the seasonal distribution of all parasitic stages and the development periods of engorged ticks under different conditions of photoperiod and temperature. All stages were found active along the entire year in the study area. Larvae peaked from May to July, nymphs peaked from July to October, and females peaked from November to March. This pattern represents a life cycle with one generation per year with most of the ticks reaching adulthood during the warmest months. The analysis of the effect of the photoperiod on the development of A. dubitatum showed no indication of morphogenetic diapause. Exposure of ticks to field conditions indicates a delay in metamorphosis of immature stages, in the oviposition of females and in the incubation of eggs, which were associated with low winter temperatures. The results indicate that though A. dubitatum has a one year life cycle, more than one cohort can co-exist within the same population in a certain interval of time. Finally, the potential role of small rodents as hosts for larvae and nymphs of A. dubitatum is confirmed.     

A survey of tick‐borne pathogens in dogs and their ticks in the Pantanal biome,Brazil

Tick and blood samples collected from domestic dogs in the Brazilian Pantanal were tested by molecular methods for the presence of tick‐borne protozoa and bacteria. Among 320 sampled dogs, 3.13% were infected by Babesia vogeli (Piroplasmida: Babesiidae), 8.75% by Hepatozoon canis (Eucoccidiorida: Hepatozoidae), 7.19% by Anaplasma platys (Rickettsiales: Anaplasmataceae), and 0.94% by an unclassified Anaplasma sp. In three tick species collected from dogs, the following tick‐borne agents were detected: (a) B. vogeli, An. platys and Ehrlichia canis (Rickettsiales: Anaplasmataceae), infecting Rhipicephalus sanguineus sensu lato (Ixodida: Ixodidae) ticks; (b) H. canis, an unclassified Anaplasma sp. and Rickettsia amblyommii (Rickettsiales: Rickettsiaceae), infecting Amblyomma cajennense sensu lato (Ixodida: Ixodidae) ticks, and (c) Rickettsia sp. strain Atlantic rainforest, an emerging human pathogen, infecting Amblyomma ovale ticks. Molecular analysis, based on a mitochondrial gene, revealed that the Am. cajennense s.l. ticks of the present study corresponded to Amblyomma sculptum, a member of the Am. cajennense species complex, and that Rh. sanguineus s.l. belonged to the tropical lineage. Whereas dogs are exposed to a number of tick‐borne bacterial and protozoan agents in the Pantanal biome, humans are potentially exposed to infection by spotted fever group rickettsiae (e.g. R. amblyommii and Rickettsia sp. strain Atlantic rainforest) because both Am. sculptum and Am. ovale are among the most important human‐biting ticks in Brazil.     

The Effect of Male Ticks on the Feeding Performance of Immature Stages of Rhipicephalus Sanguineus and Amblyomma Americanum (Acari: Ixodidae)

A unique group of immunoglobulin-binding proteins (IGBPs), produced by ixodid male ticks during the latter half of their prolonged feeding period, improves the feeding performance of co-feeding females. As a follow-up to this observation, we investigated whether male tick feeding also affects the feeding of other developmental stages. Immature stages of Rhipicephalus sanguineus (Latreeille) and Amblyomma americanum (L.) were fed on rabbits in the presence or absence of conspecific males. The mean weight of larvae and nymphs of both species that fed around males and detached from the host on the first day of dropping was significantly higher than when the immature ticks fed on rabbits in the absence of males. However, larvae of both species and nymphs of R. sanguineus that fed slower and detached on the second day of dropping did not show significant differences in weight. A similar pattern was observed for A. americanum nymphs although, unlike R. sanguineus, the presence of males also influenced the feeding performance of the nymphs that fed slowly and detached on the second day of drop-off. The improved feeding performance demonstrated by immature ticks in the presence of males may be due to immunomodulatory saliva proteins, such as immunoglobulin-binding proteins (IGBPs) that are introduced into the co-feeding site. The results are considered in relation to the distribution of ixodid tick species on their natural hosts.     

Divergent environmental preferences and areas of sympatry of tick species in the Amblyomma cajennense complex (Ixodidae)

Four species of Neotropical ticks, Amblyomma mixtum, Amblyomma cajennense, Amblyomma tonelliae and Amblyomma sculptum (formerly included in the catch-all name A. cajennense), have an allopatric distribution in much of their range, with areas of parapatry for at least two of them. We inferred the abiotic niches of these organisms using coefficients of a harmonic regression of the temperature and the Normalized Difference Vegetation Index (NDVI, reflecting plant stress) from remotely sensed data from MODIS satellites with 0.05° spatial resolution. Combinations of coefficients describing the phenology of these two variables pointed to divergent niche preferences, compatible with previous events of vicariance among the species. Amblyomma cajennense has been recorded in areas with small variations in temperature and NDVI. The remaining species were recorded in areas with large variations. The maximum environmental niche overlap was ∼73.6% between A. mixtum and A. cajennense and 73.5% between A. tonelliae and A. sculptum. Projecting these inferences on the geographical space revealed probable areas of sympatry or parapatry between A. mixtum and A. cajennense or between A. tonelliae and A. sculptum, the latter of which was confirmed with field collections. The A. sculptum distribution overlaps with that of A. tonelliae in northern Argentina and Paraguay; parapatry occurs at one extreme of the conditions occupied by both species. Compared with areas of allopatry, sites with both species had consistently lower temperatures, except for 10–12 weeks during the summer, and higher NDVI values throughout the year. We hypothesise that the overlap between A. tonelliae and A. sculptum resulted from secondary contact between populations, with A. sculptum adapting to sites with high water availability to balance high summer temperatures. Additional surveys of the areas of spatial overlap among these species are necessary to elucidate the forces driving their evolution and their adaptation to the environment.     

The natural hosts for larvae and nymphs of Amblyomma neumanni and Amblyomma parvum (Acari: Ixodidae)

Based on the hypothesis that birds and rodents are important hosts for subadults of the Neotropical Amblyomma neumanni and Amblyomma parvum ticks, a survey of these type of hosts was carried out from July 2004 to March 2006, in Quilino (A. parvum) and Dean Funes (A. neumanni), Córdoba province, Argentina. Additionally, monthly tick counts were performed on cattle and goats with occasional tick search in other domestic hosts. Records of questing height of subadult ticks on vegetation were also carried out monthly. Rodents (n = 123) and birds (n = 122) captured in Dean Funes showed no infestation with A. neumanni. Apart of few nymphs found on horses, all larvae and nymphs of A. neumanni were on cattle with a larval prevalence and mean number of 22.2%, and 7.7 ± 22.52, respectively, and a prevalence of nymphs of 47.8% with a mean of 7.9 ± 18.49. The average questing height of larvae and nymphs of A. neumanni was 23.5 ± 17.1 cm and 30.7 ± 26.7 cm, respectively. A total of 138 rodents and 130 birds were captured in Quilino but the Caviidae rodent Galea musteloides carried 99.3% of larvae and 99.8% of nymphs of A. parvum, and no immature stages were detected on cattle, goat or vegetation. Tick counts on G. musteloides (n = 74) showed a prevalence of 42% and a mean number of 9.9 ± 24.83 for larvae, while nymphal infestation had a prevalence of 56.5% and a mean of 8.7 ± 11.31. Cattle appear to be suitable hosts to sustain the complete cycle of A. neumanni in nature (adult ticks infest cattle too) and questing height of subadults indicates that they are expecting to feed on medium and large-sized mammals, such as cattle and other ungulates. At least in the study site, G. musteloides is the principal host for the survival strategy of A. parvum subadults; adult ticks are common on cattle and goats. These hosts are introduced in the Neotropics but A. neumanni was able to develop a surrogate cycle independent of native hosts while A. parvum still depends on probably primeval hosts to sustain their larvae and nymphs.     

Amblyomma Tigrinum (Acari: Ixodidae) in Relation to Phytogeography of Central-Northern Argentina with Notes on Hosts and Seasonal Distribution

The findings of Amblyomma tigrinum in continental Argentina north of 40°S are presented according to phytogeographic domains (Andean–Patagonic, Amazonian and Chaco) and the seasonal distribution is depicted on a monthly basis. A total of 718 adult ticks and four nymphs were found. A. tigrinum ticks were present in all domains. Adult ticks were found all year round but they were more abundant during the summer. Most ticks were found on domestic dogs but the survey has a bias to domestic hosts. It is speculated that the cycle of immature is bound to shelters that mitigate extreme climatic conditions, thus explaining the finding of this tick species in contrasting ecological areas.