RESUMO
The hard tick family Ixodidae currently comprises 762 species worldwide, but an analysis of the occurrence of these species in the world´s countries, territories, zoogeographic regions (Afrotropical, Australasian, Nearctic, Neotropical, Oriental, Palearctic) and remote islands has not been attempted since 2009. Here, we present and critically discuss distributional data for all currently accepted ixodid species known from 226 countries and territories in six zoogeographic realms. This summary of ixodid tick biogeography should prove to be a valuable reference for biologists interested in ticks as organisms as well as specialists focusing on tick-borne diseases. Data for all species treated here were derived from a literature search that ended on March 31, 2022.
Assuntos
Ixodidae , Doenças Transmitidas por Carrapatos , Carrapatos , AnimaisRESUMO
The aim of this research was to analyze and model the aptitude of temperate areas to support permanent populations of the cattle tick Rhipicephalus microplus, which is principally distributed in tropical and subtropical areas. This work integrated field-derived data of tick development with temperature and land-based models of tick spread in Argentina. The integrated analysis of the results suggest that approximately 31°S is the southern limit where R. microplus finds appropriate climatic conditions to be established permanently. The establishment of permanent populations of R. microplus south of this latitudinal threshold is currently restricted because the low temperatures in autumn and winter inhibit the development of its eggs, but the introduction of cattle infested with R. microplus from early spring to late summer in temperate areas could produce engorged females laying eggs that would originate viable larvae from late spring to winter. The comparison of the temperature-based maps of habitat suitability with those obtained considering the lands suitable for livestock grazing, clearly shows that the models based only on climatic variables overestimate the potential dispersal of the cattle tick. The outcomes of this study suggest that an increase of temperature in the months of autumn and winter around 2°-2.75 °C should be necessary for the establishment of permanent populations of R. micoplus in the region belonging to temperate areas. This would allow that a tick generation emerged in early spring due to the overwintering of eggs and larvae originated from females detached from cattle during autumn or early winter.
Assuntos
Doenças dos Bovinos , Ecossistema , Rhipicephalus , Infestações por Carrapato , Animais , Argentina , Bovinos , Feminino , Larva , Óvulo , Estações do Ano , Infestações por Carrapato/veterináriaRESUMO
The aim of this work is to report the presence of resistance to fluazuron in a population of Rhipicephalus microplus in Argentina. The evidence was obtained from field and in vitro trials. In the field trial, cattle infested with ticks was treated with two commercial formulations of fluazuron. The in vitro trial (adult immersion test, AIT) was performed by using technical grade fluazuron. In the field trial, there were no significant differences between the treated and control groups between days 2 and 34 post-treatment. The only exceptions (treated group I in day 14 post-treatment, treated group II in days 23 and 29 post-treatment) had a significantly lower tick load than the untreated group, but the efficacy was not higher than 70%. Viable engorged females were collected on both groups of treated bovines in all counts, and the production of viable larvae was not precluded with the application of the two commercial formulations of fluazuron evaluated in this study. The results obtained with the in vitro assay (AIT) also indicate that the R. microplus population tested in this work has a higher level of resistance to fluazuron than another susceptible field strain. The integrated analysis of the field and in vitro trials clearly reveals the emergence of resistance to fluazuron in a R. microplus population from Argentina. This diagnosis of resistance does not imply that the fluazuron has lost its functionality at a regional scale, but it highlights the need to establish control strategies that minimize the use of this drug in order to preserve its functionality as an acaricide.
Assuntos
Acaricidas , Doenças dos Bovinos , Rhipicephalus , Infestações por Carrapato , Acaricidas/uso terapêutico , Animais , Argentina , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/prevenção & controle , Feminino , Compostos de Fenilureia , Infestações por Carrapato/tratamento farmacológico , Infestações por Carrapato/prevenção & controle , Infestações por Carrapato/veterináriaRESUMO
The aim of this study was to report the finding of a nymph attached to an Argentinean tourist returning from South Africa. The nymph specimen was morphologically analysed, submitted to DNA extraction and amplifying the 16S rRNA mitochondrial gene. Additionally, the nymph DNA was screened for Rickettsia, Ehrlichia and Anaplasma infection. The nymph was determined to belong to Amblyomma marmoreum species complex. No specific diagnosis was achieved because the comparative descriptions of species in this complex contain important discordances, and the DNA sequence obtained in the present study is positioned within the same clade with sequences of A. marmoreum see above, but the genetic divergence with them (4.96 and 5.76%) indicate that they belong to different species. No DNA of the Rickettsiales order bacterial was detected in the A. marmoreum species complex nymph.
Assuntos
Rickettsia , Carrapatos , Animais , Argentina , RNA Ribossômico 16S/genética , Rickettsia/genética , África do Sul , Carrapatos/microbiologiaRESUMO
Females, nymphs, and larvae of Ixodes silvanus n. sp. collected from birds and from the vegetation in northwestern Argentina (Yungas Phytogeographic Province) are described herein. The new species belongs to the subgenus Trichotoixodes (Acari: Ixodidae). The female is diagnosed by a combination of the following characters: scutum with setae moderately long and more numerous in central field, fewer and moderately long setae on lateral fields, and inconspicuous setae in anterior field; basis capituli subtriangular dorsally; porose areas large and irregular in shape, lacking distinct margins; auriculae with straight edges diverging posterolaterally and ending with small blunt processes; hypostome narrow and pointed with dental formula 4/4 in the anterior third, then 3/3 and 2/2 near the base; coxae I with two spurs, sub-equal in size, internal slightly slimmer than external. The nymph is diagnosed by notum with numerous and long setae, ventral surface covered by numerous whitish setae, scutum with short scapulae and few and shallow punctations, setae on scutum few, short and irregularly distributed, basis capituli sub-triangular dorsally with posterior margin straight, cornua large and directed postero-laterally, auriculae large and projected laterally, lateral margin of basis capituli above auriculae with a lateral and triangular projection, hypostome pointed with dental formula 3/3 in the anterior third and then 2/2, and coxa I with two short, sub-equal, triangular spurs. The diagnostic characters of the larva are: basis capituli dorsally sub-triangular with lateral angles acute and posterior margin straight, auriculae as large triangular lateral projections, hypostome with apex bluntly pointed and dental formula 3/3 in the anterior third and then 2/2, coxa I with two short, sub-equal, triangular spurs, and pattern of dorsal and ventral body setae. This new species is phylogenetically related to Ixodes brunneus, Ixodes turdus and Ixodes frontalis, and the principal hosts for all its parasitic stages are birds.
Assuntos
Ixodes/anatomia & histologia , Ixodes/classificação , Animais , Argentina , DNA Espaçador Ribossômico/análise , Complexo IV da Cadeia de Transporte de Elétrons/análise , Feminino , Ixodes/crescimento & desenvolvimento , Ixodes/ultraestrutura , Larva/anatomia & histologia , Larva/classificação , Larva/crescimento & desenvolvimento , Larva/ultraestrutura , Microscopia , Microscopia Eletrônica de Varredura , Ninfa/anatomia & histologia , Ninfa/classificação , Ninfa/crescimento & desenvolvimento , Ninfa/ultraestrutura , Filogenia , RNA Ribossômico 16S/análiseRESUMO
References to the descriptions and redescriptions of the 742 species of Ixodidae published from 1758 to December 31, 2019 are compiled, with the goal of enabling tick taxonomists to readily access this diffuse and often confusing literature. Additionally, data resulting from this effort are critically analyzed to demonstrate the problems attending correct identification of several tick species that are of medical, veterinary and/or evolutionary importance, and to highlight the need for new or enhanced diagnostic techniques. Recent morphological and molecular studies indicate that some ixodid species names represent more than one taxon; therefore, it is expected that new species will be described in the near future, based partly on material already deposited in museums around the world.
Assuntos
Ixodidae , Carrapatos , Animais , Evolução BiológicaRESUMO
Resistance to ivermectin in populations of the cattle tick Rhipicephalus microplus in Argentina was diagnosed in this work. The in vitro larval immersion test (LIT) was used to determine quantitatively the levels of resistance to ivermectin in different populations of R. microplus. Additionally, field trials to control natural infestations of R. microplus on cattle with a commercial formulation of ivermectin 3.15% were carried and jointly analyzed with the in vitro assays. The phenotypic response of the populations analyzed was not uniform. Five of them were classified as susceptible, four populations as resistant, and one in the category "incipient resistance". Regarding the field trials, the therapeutic efficacy in a population classified with LIT as susceptible achieved values higher than 94% two weeks after treatment, and no reproductively viable females were observed after the second day post-treatment. Conversely, the values of efficacy percentage in a population (named as "San Martín") classified with LIT in the category "incipient resistance" never exceeded the 70.8%, and engorged females were collected in practically all counts. The population "San Martín" was classified in the category "incipient resistant" with LIT analysis, but the field trial unambiguously shows that this tick population is resistant. The comparison of the results obtained with LIT in vitro assays and through field trials shows that biased estimations of resistance levels may occur when resistance ratios (RR) values are ≤2, and additional field efficacy trials could be needed to know with precision the status of the tick populations evaluated.
Assuntos
Resistência a Inseticidas , Inseticidas/farmacologia , Ivermectina/farmacologia , Rhipicephalus/efeitos dos fármacos , Infestações por Carrapato/veterinária , Animais , Argentina , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Feminino , Larva , Infestações por Carrapato/tratamento farmacológicoRESUMO
In a recent study, we relegated the taxon Ixodes aragaoi Fonseca, 1935 to a junior synonym of Ixodes fuscipes Koch, 1844, and reinstated Ixodes spinosusNeumann, 1899 (a former synonym of I. fuscipes) to a valid species. We examined all lots of ticks formerly identified as I. fuscipes or I. aragaoi in three tick collections of Brazil. Through morphological analysis, some of the examined specimens could not be assigned to either I. fuscipes or I. spinosus based on the examination of the type specimens of these two species. Herein, we report these ticks to represent three different species: Ixodes catarinensis n. sp. Onofrio & Labruna, Ixodes lasalleiMéndez Arocha and Ortiz, 1958, and Ixodes bocatorensisApanaskevich and Bermúdez, 2017. The latter two species are reported for the first time in Brazil. Phylogenetic analysis inferred from the tick 16S rRNA gene partial sequences corroborated our morphological analysis, indicating that I. spinosus, I. lasallei, I. bocatorensis, and I. catarinensis n. sp. form a natural group of neotropical ticks. With the present study, the number of Ixodes species in Brazil increases from 9 to 12. We propose a new identification key for females and males of Ixodes species currently recognized in Brazil.
Assuntos
Distribuição Animal , Ixodes/classificação , Ixodes/fisiologia , Animais , Brasil , Feminino , Ixodes/anatomia & histologia , Ixodes/genética , Masculino , Filogenia , RNA Ribossômico 16S/análiseRESUMO
Ixodes fuscipes Koch, 1844, described from Brazil, has been considered a valid species with records from Brazil and Peru. Ixodes spinosus Neumann, 1899, also described from Brazil, has been considered a synonym of I. fuscipes. In 2014, Ixodes aragaoi Fonseca, 1935 was redescribed as a valid species for Brazil and Uruguay. Until the present study, one major difference between the females of I. fuscipes and I. aragaoi was the horn-like auriculae in the former versus the ridge-like auriculae in the later, but this morphological difference was not supported after examination of the holotype of I. fuscipes and a syntype female of I. spinosus. Surprisingly, we found the type of I. fuscipes to have ridge-like auriculae, in contrast to the horn-like auriculae of I. spinosus. Comparisons of the I. fuscipes holotype with the syntypes of I. aragaoi revealed that they correspond to the same species. Therefore, we redescribe I. fuscipes, relegate I. aragaoi to a junior synonym of I. fuscipes, and reinstate I. spinosus as a valid species. After examining all lots of I. fuscipes in four tick collections, no specimen was recognized as I. fuscipes when compared with the type specimen of this taxon. On the other hand, specimens previously identified as I. aragaoi are now confirmed as I. fuscipes, with bona fide records for Brazil and Uruguay. Some of the specimens previously reported as I. fuscipes are now confirmed as I. spinosus, with records in two Brazilian biomes, Amazon and Atlantic rainforest. We present lists of the ticks examined in this study, with their current taxonomic status.
Assuntos
Ixodes/classificação , Animais , Brasil , Feminino , Ixodes/anatomia & histologia , Ixodes/crescimento & desenvolvimento , Larva/anatomia & histologia , Larva/classificação , Larva/crescimento & desenvolvimento , Masculino , Ninfa/anatomia & histologia , Ninfa/classificação , Ninfa/crescimento & desenvolvimento , UruguaiRESUMO
The goal of this study was to clarify the taxonomic status of the Ixodes ricinus complex in the Southern Cone of America, by using morphological characters and molecular markers (mitochondrial 16SrDNA and cox1 genes). The morphological analysis indicates that three different taxa of the I. ricinus complex occur in this region: Ixodes pararicinus, Ixodes aragaoi, and Ixodes sp. cf. I. affinis. The most prominent diagnostic character among them is the size of scutal punctations in both male and female ticks. In the males of Ixodes sp. cf. I. affinis, the punctations on the central field and along the median marginal groove of the scutum are clearly larger than in the males of I. aragaoi and I. pararicinus, while the punctations of I. aragaoi are larger but less numerous than in I. pararicinus. The punctations in Ixodes sp. cf. I. affinis females are larger and deeper than in females of I. aragaoi and I. pararicinus, and those of I. aragaoi are slightly larger than in I. pararicinus. The length of the lateral posterior denticles of the male hypostome is comparatively longer in I. aragaoi than in the other two species, and longer in Ixodes sp. cf. I. affinis than in I. pararicinus. In the 16S analysis, I. pararicinus and I. aragaoi are monophyletic (99% and 98% bootstrap support, respectively), while Ixodes cf. I. affinis does not represent a single lineage. In the cox1 analysis, both I. pararicinus and I. aragaoi are well-defined taxa, but the bootstrap support for Ixodes sp. cf. I. affinis is low (67%). In general, there are considerable 16SrRNA differences among lineages of Ixodes sp. cf. I. affinis from different geographical areas. These results may be indicative of the existence of different species. The populations morphologically compatible with I. affinis from Argentina, Colombia, Panama, Belize, and USA should be provisionally named as Ixodes sp. cf. I. affinis until an integrative taxonomic work with further evidence redefines whether or not this taxon actually represents a species complex.