First record of Rhipicephalus (Boophilus) microplus in Ghana, a potential risk to livestock production.

Ticks are a public health threat due to their tendency to spread pathogens that affect humans and animals. With reports of Rhipicephalus (Boophilus) microplus invasion in neighbouring countries, there is the risk of this species invading Ghana through livestock trade. Previous identification of tick species in Ghana has been based on morphological identification, which can be ineffective, especially with damaged tick specimens or engorged nymphs. This study focused on the Kassena-Nankana District, which serves as a trade route for cattle into Ghana, to determine the presence of R. microplus. Three genera of ticks were identified as Amblyomma (70.9%), Hyalomma (21.3%) and Rhipicephalus (7.8%). The engorged nymphs that could not be identified morphologically were analyzed using primers that target the mitochondrial 16S rRNA gene. This study reports the first record of R. (B.) microplus in Ghana. Furthermore, R. microplus constituted 54.8% of the Boophilus species collected in this study. This finding is an addition to the diverse tick species previously collected in Ghana, most of which are of veterinary and public health importance. With reports of acaricide resistance in R. microplus and its role in spreading infectious pathogens, the detection of this species in Ghana cannot be overlooked. Nationwide surveillance will be essential to ascertain its distribution, its effects on cattle production, and the control measures adopted.

Adaptive radiation and speciation in Rhipicephalus ticks: A medley of novel hosts, nested predator-prey food webs, off-host periods and dispersal along temperature variation gradients.

Rhipicephalus are a species-diverse genus of ticks, mainly distributed in the Afrotropics with some species in the Palearctic and Oriental regions. Current taxonomic consensus comprise nine informal species groups/lineages based on immature morphology. This work integrates biogeographic, ecological and molecular lines of evidence to better understand Rhipicephalus evolution. Phylogenetic analysis based on four genes (12S, 16S, 28S-D2 and COI) recovered five distinct clades with nine descendant clades that are generally congruent with current taxonomy, with some exceptions. Historical biogeography is inferred from molecular divergence times, ancestral distribution areas, host-use and climate niches of four phylogenetically significant bioclimatic variables (isothermality, annual, seasonal and diurnal temperature range). Novel hosts enabled host-linked dispersal events into new environments, and ticks exploited new hosts through nested predator-prey connections in food webs. Diversification was further induced by climate niche partitioning along gradients in temperature range during off-host periods. Ancestral climate niche estimates corroborated dispersal events by indicating hypothetical ancestors moved into environments with different annual and seasonal temperature ranges along latitudinal gradients. Host size for immature and adult life stages was important for dispersal and subsequent diversification rates. Clades that utilise large, mobile hosts (ungulates and carnivores) early in development have wider geographic ranges but slower diversification rates, and those utilising small, less mobile hosts (rodents, lagomorphs and afroinsectivores) early in development have smaller ranges but higher diversification rates. These findings suggest diversification is driven by a complex set of factors linked to both host-associations (host size, ranges and mobility) and climate niche partitioning along annual and seasonal temperature range gradients that vary with latitude. Moreover, competitive interactions can reinforce these processes and drive speciation. Off-host periods facilitate adaptive radiation by enabling host switches along nested predator-prey connections in food webs, but at the cost of environmental exposure that partitions niches among dispersing progenitors, disrupting geneflow and driving diversification. As such, the evolution and ecological niches of Rhipicephalus are characterised by trade-offs between on- and off-host periods, and these trade-offs interact with nested predator-prey connections in food webs, host-use at different life stages, as well as gradients in annual and seasonal temperature ranges to drive adaptive radiation and speciation.

Mitochondrial and nuclear multilocus phylogeny of Rhipicephalus ticks from Kenya.

The morphological diversity of African ticks of the genus Rhipicephalus and subgenus Boophilus have been studied in detail. However, their taxonomy remains poorly resolved with limited molecular studies performed to improve inter-species discrimination. Herein, ribosomal cytochrome c oxidase I (COI), 12S ribosomal DNA (12S rDNA) and nuclear ribosomal DNA internal transcriber spacer 2 (ITS2) were analyzed in Rhipicephalus tick populations in Kenya. While the morphological and molecular criteria separated R. e. evertsi, R. pulchellus and R. appendiculatus from other members of the genus, except the morphologically similar sibling species R. zambeziensis, this was not the case for other tick populations. COI sequences of Rhipicephalus ticks from Ruma National Park (RNP) in Southwestern Kenya, that were morphologically similar to R. praetextatus/R. simus, a formed distinct clade and barcode gap group. 12S rDNA haplotypes of this population were 99% identical to a GenBank accession of R. muhsamae which is thought to be endemic in West and Central Africa. However, the ITS2 locus indicated that the RNP samples were genetically closest to ticks identified morphologically as R. praetextatus. The COI and 12S rDNA haplotype sequences of R. praetextatus clustered closely with R. simus reference sequences though the two species occurred in distinct barcode gap groups. Our results suggest that the R. simus/R. praetextatus/R. muhsamae comprise a closely related tick species complex found across sub-Saharan Africa and includes the yet to be described RNP population. More studies on the biology, ecology and genomics of all life stages of tick species in the complex may clarify their taxonomic status. A continent-wide study that combines morphology, DNA marker sequencing and emerging methods, such as mass spectrometry and whole-genome resequencing may reveal the diversity and distribution of taxa within the genus Rhipicephalus in sub-Saharan Africa.

The genetic relationship between R. microplus and R. decoloratus ticks in South Africa and their population structure.

Rhipicephalus microplus and R. decoloratus are one-host ticks that preferentially feed on cattle. They are capable of transmitting various tick-borne pathogens which may be detrimental to the agricultural and livestock industry in South Africa. Previous studies have shown that R. microplus forms five lineages in the R. microplus complex, segregating into different geographical areas based on mitochondrial markers. This study examined the phylogenetic relationship within and between R. microplus and R. decoloratus using the nuclear internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome oxidase subunit I (COI) genes. The results showed that the nuclear ITS2 marker is informative for interspecific variation but lacks the resolution for intraspecific variation. Analysis of the mitochondrial COI gene revealed that R. microplus ticks from South Africa grouped into a clade comprised of ticks from Asia and South America. The population structure of these two tick species was also investigated using novel microsatellite markers. Population structure analyses revealed that both the R. microplus and R. decoloratus populations presented with two genetic clusters. Rhipicephalus microplus ticks from the Kwa-Zulu Natal (KZN) province belonged to cluster 1, and those from the Eastern Cape (EC) province predominantly grouped into cluster 2. No observable population structure was noted for R. decoloratus. The overlap of genetic clusters in both species could be attributed to inbreeding between the regions by unrestricted movement of cattle across provinces. Such movement promotes tick mobility, gene flow and the homogenisation of tick populations.

Phylogenetic insights on Mediterranean and Afrotropical Rhipicephalus species (Acari: Ixodida) based on mitochondrial DNA.

A multigene phylogeny including 24 Rhipicephalus species from the Afrotropical and Mediterranean regions, based on mitochondrial DNA genes (COI, 12S and 16S), was constructed based on Bayesian inference and maximum likelihood estimations. The phylogenetic reconstruction revealed 31 Rhipicephalus clades, which include the first molecular records of Rhipicephalus duttoni (Neumann), and Rhipicephalus senegalensis (Koch). Our results support the R. pulchellus, R. evertsi and R. pravus complexes as more phylogenetically close to Rhipicephalus (Boophilus) than to the remaining Rhipicephalus clades, suggesting two main monophyletic groups within the genus. Additionally, the phenotypic resembling R. sanguineus s.l. and Rhipicephalus turanicus (Pomerantsev) are here represented by nine clades, of which none of the R. turanicus assemblages appeared as distributed in the Iberian Peninsula. These results not only indicate that both species include more cryptic diversity than the already reported, but also suggest that R. turanicus distribution is less extended than previously anticipated. This analysis allowed to improve species identification by exposing cryptic species and reinforced mtDNA markers suitability for intra/inter-species clarification analyses. Incorporating new species molecular records to improve phylogenetic clarification can significantly improve ticks' identification methods which will have epidemiologic implications on public health.

Morphological and molecular divergence of Rhipicephalus turanicus tick from Albania and China.

Rhipicephalus turanicus is an important tick species potentially carrying tick-borne pathogens. Several tick species have obvious subspecies divergence. However few studies aimed to examine the existence of divergence within R. turanicus. Therefore, a detailed morphological and molecular analysis was conducted for comparing R. turanicus from the Mediterranean Basin (represented by Albania) and Central Asia (Northwestern China). Altogether 315 adult ticks of R. turanicus (103 from Albania and 212 from China) were morphologically and molecularly analysed. DNA samples were used for mitochondrial 16S rRNA and cox1 gene sequences analysis. In addition, as potentially genetic markers, three fragments including partial nad1-16S rRNA, nad2-cox1, cox1-tRNA-Lys, were designed and then phylogenetically analyzed. Based on detailed morphological observations, only basis capituli length:width ratio (females), the length, the width and the length:width ratio of the scutum (males) had differences between R. turanicus from China and Albania. Gene divergences of 16S rRNA, cox1, partial nad1-16S rRNA, nad2-cox1 and cox1-tRNA-Lys from China and Albania ticks were 3.53-4.84, 3.57-4.92, 3.57-4.07, 3.57-4.39 and 3.18-4.69%, respectively. The evaluated five genetic markers revealed two phylogenetic branches in R. turanicus. Obvious differences exist within R. turanicus based on morphological and genetic analysis. Three newly designed genetic markers (partial nad1-16S rRNA, nad2-cox1 and cox1-tRNA-Lys) in this study may be suitable genetic tools for identification and analysis in R. turanicus. Subspecies analysis of R. turanicus from other regions of the world should be initiated in the future.

Diversity of tick species on domestic animals in Shandong Province, China, using DNA barcoding.

Ticks are considered to be second only to mosquitoes as vectors of diseases. In recent years, severe fever with thrombocytopenia syndrome, a new emerging tick-borne disease has been detected in many areas of China, including Shandong Province, Eastern China. Here, we report the tick species diversity based on surveys between 2014 and 2016 covering 16 locations in seven cities of Shandong. Based on DNA barcoding, 1859 ticks belonging to three species were identified: Haemaphysalis longicornis, Rhipicephalus turanicus and Haemaphysalis verticalis. Samples of the same species clustered together in a neighbor-joining phylogenetic tree, with intraspecific distances between 0 and 3.0% and interspecific distances ranged between 15.5 and 24.3%. Goats and dogs were the major hosts of ticks and H. longicornis was regarded as predominant tick species of Shandong. In order to reduce tick populations and prevent tick-borne diseases, effective control measures should be implemented on human and domestic animals, respectively.

Rhipicephalus rossicus, a neglected tick at the margin of Europe: a review of its distribution, ecology and medical importance.

Rhipicephalus rossicus (Ixodida: Ixodidae) is a three-host tick with a broad host spectrum that includes wild animals, pets, livestock and humans. Despite its local abundance in certain areas, most of the available information on R. rossicus was published decades ago, mainly by former soviet authors. Its distribution largely overlaps the Eurasian steppe. However, its range may be more extensive than is currently known because this species may have been misidentified as Rhipicephalus sanguineus, principally in areas where the latter species is present. Although R. rossicus has been occasionally reported to feed on people, little attention has been given to its medical importance. It has been shown to have a vectorial role in the transmission of Francisella tularensis, Crimean-Congo haemorrhagic fever virus and West Nile virus. However, the vectorial importance of R. rossicus may be significantly greater, mainly as the closely related species R. sanguineus s.l. is known to transmit a very wide spectrum of pathogens. The probably underestimated vectorial role of R. rossicus may represent a hidden public health threat.

RmKK, a tissue kallikrein inhibitor from Rhipicephalus microplus eggs.

Rhipicephalus microplus is an important ectoparasite that is responsible for transmission of anaplasmosis and babesiosis to cattle. Tissue kallikrein inhibitors might play an important role in R. microplus eggs. In the present work, we purified and characterized, a tissue kallikrein inhibitor presents in R. microplus eggs (RmKK), a protein which contains two Kunitz domain in tandem. Purified inhibitor was confirmed by amino terminal determination and its dissociation constant (Ki) for bovine trypsin and porcine pancreatic kallikrein were 0.6 nM and 91.5 nM, respectively. Using a cDNA library from R. microplus midgut, we cloned the cDNA fragment encoding mature RmKK and expressed the protein in Pichia pastoris system. Recombinant RmKK was purified by ion exchange chromatography and presented molecular mass of 16.3 kDa by MALDI-TOF analysis. Moreover, RmKK showed a tight binding inhibition for serine proteases as bovine trypsin (Ki=0.2 nM) and porcine pancreatic kallikrein (PPK) (Ki=300 nM). We performed, for the first time, the characterization of a tissue kallikrein inhibitor presents in R. microplus eggs, which the transcript is produced in the adult female gut. BmKK seems to be the strongest PPK inhibitor among all BmTIs present in the eggs and larvae (Andreotti et al., 2001; Sasaki et al., 2004). This data suggests that BmKK may participate in the development of tick egg and larvae phase.

Phylogenetic analysis of mitochondrial genome sequences indicates that the cattle tick, Rhipicephalus (Boophilus) microplus, contains a cryptic species.

Cattle ticks of the subgenus Rhipicephalus (Boophilus) are major agricultural pests worldwide, causing billions of dollars in losses annually. Rhipicephalus (Boophilus) annulatus and R. microplus are the most well-known and widespread species, and a third species, R. australis, was recently reinstated for 'R. microplus' from Australia and parts of Southeast Asia. We use mitochondrial genome sequences to address the phylogenetic relationships among the species of the subgenus Boophilus. We sequenced the complete or partial mitochondrial genomes of R. annulatus, R. australis, R. kohlsi, R. geigyi, and of three geographically disparate specimens of R. microplus from Brazil, Cambodia and China. Phylogenetic analyses of mitochondrial genomes, as well as cox1 and 16S rRNA sequences, reveals a species complex of R. annulatus, R. australis, and two clades of R. microplus, which we call the R. microplus complex. We show that cattle ticks morphologically identified as R. microplus from Southern China and Northern India (R. microplus clade B) are more closely related to R. annulatus than other specimens of R. microplus s.s. from Asia, South America and Africa (R. microplus clade A). Our analysis suggests that ticks reported as R. microplus from Southern China and Northern India are a cryptic species. This highlights the need for further molecular, morphological and crossbreeding studies of the R. microplus complex, with emphasis on specimens from China and India. We found that cox1 and, to a lesser extent, 16S rRNA were far more successful in resolving the phylogenetic relationships within the R. microplus complex than 12S rRNA or the nuclear marker ITS2. We suggest that future molecular studies of the R. microplus complex should focus on cox1, supplemented by 16S rRNA, and develop nuclear markers alternative to ITS2 to complement the mitochondrial data.

A family of serine protease inhibitors (serpins) in the cattle tick Rhipicephalus (Boophilus) microplus.

Proteins belonging to the serine protease inhibitor (serpin) superfamily play essential roles in many organisms. In arthropods these proteins are involved in innate immune system, morphogenesis and development. In mammals serpins regulate pathways that are essential to life such as blood coagulation, fibrinolysis, inflammation and complement activation, some of which are considered the host's first line of defense to hematophagous and/or blood dueling parasites. Thus, it is hypothesized that ticks use serpins to evade host defense, facilitating parasitism. This study describes eighteen full-length cDNA sequences encoding serpins identified in Rhipicephalus (Boophilus) microplus, here named RmS 1-18 (R. microplus serpin). Spatial and temporal transcriptional profiling demonstrated that R. microplus serpins are transcribed during feeding, suggesting their participation in tick physiology regulation. We speculate that the majority of R. microplus serpins are conserved in other ticks, as indicated by phylogeny analysis. Over half of the 18 RmSs are putatively functional in the extracellular environment, as indicated by putative signal peptides on 11 of 18 serpins. Comparative modeling and structural-based alignment revealed that R. microplus serpins in this study retain the consensus secondary of typical serpins. This descriptive study enlarges the knowledge on the molecular biology of R. microplus, an important tick species.

Identification and characterization of Rhipicephalus (Boophilus) microplus and Haemaphysalis bispinosa ticks (Acari: Ixodidae) of northeast India by ITS2 and 16S rDNA sequences and morphological analysis.

To investigate and identify the ticks prevalent in the North East part of India, scanning electron microscope (SEM) and DNA sequence of nuclear second internal transcribed spacer (ITS2) and mitochondrial 16S ribosomal DNA (rDNA) were used. Based on the morphological and molecular analysis, the ticks infesting cattle of North East India were found to be Rhipicephalus (Boophilus) microplus and Haemaphysalis bispinosa. ITS2 and 16S rDNA sequence from R. (B.) microplus and H. bispinosa were amplified using universal and gene specific primers, sequenced and analysed. The length of the amplified ITS2 sequence of R. (B.) microplus and H. bispinosa, were found to be approximately 1,500 and 1,700 bp, respectively. The length of the 16S rDNA sequences in both the ticks was found to be similar in size, but they differ in their base pair constitutions. This is the first report of the nucleotide sequences of ITS2 and 16S rDNA of H. bispinosa. Phylogenetic analysis revealed that H. bispinosa is a close relative of H. longicornis. A polymerase chain reaction-restriction fragment length polymorphism diagnostic tool was developed based on HindIII digestion of ITS2 in order to facilitate the identification of these two species which cannot be distinguished once it is fully-fed. Present study describes the use of SEM and 16S rDNA/ITS2 based molecular analysis in identification and differentiation of fully fed tick species.

Revealing tick diversity: Chemical profiling and dynamics in scanning microscopy and molecular phylogenetics.

This study presents a comprehensive investigation into the evolutionary trajectories of Rhipicephalus ticks (Ixodidae) through the interpretation of molecular phylogenetics, elucidating their chromatographic spectrum. The use of advanced chromatographic tools in this study explored the dynamics chemical profiling, providing valuable insights into the evolutionary history and ecological adaptations. Prevalence of Rhipicephalus ticks was 4.5% in sheep and 3.9% in goats. The ITS2 sequence of the Rhipicephalus sanguineus (OK642408) and Rhipicephalus microplus (OK642409) form a distinct clade with sequences from other countries. The 16S rRNA sequences of R. sanguineus (OK560870) clustered with sequences form three lineages, tropical, temperate, and south-eastern. The Cox I gene-identified Rhipicephalus turanicus (OK623472) and R. microplus (OK623463) form separate clades with sequences. The HPLC chromatogram of tick samples reveals a diverse array of identified hydrocarbons, explained the complex chemical composition of their exoskeletons. This analytical approach provides valuable insights into the specific hydrocarbon profiles, allowing for potential applications in species differentiation, ecological studies, and a deeper understanding of the functional roles played by hydrocarbon compounds in tick physiology. The findings revealed the potential of applying molecular phylogenetics tools with chromatography not only to enhance our understanding of tick evolution but also to inform strategies for disease control and management in regions where Rhipicephalus ticks (Ixodidae) are endemic. RESEARCH HIGHLIGHTS: Chemical mapping utilizing advanced chromatographic techniques. Scanning microscopic insights high-resolution scanning tool to observe structural and morphological features of ticks at a molecular level. Molecular phylogeny data elucidate the evolutionary relationships among tick species.

Description of Rhipicephalus hibericus sp. nov. (Ixodoidea: Ixodidae), a species of the Rhipicephalus sanguineus group in southwestern Europe.

We describe all the life stages of Rhipicephalus hibericus n. sp., provide the types, and present molecular support for a new species of the Rhipicephalus sanguineus sensu lato group, present in southwestern Europe, that has been historically confused with Rhipicephalus turanicus Pomerantzev, 1940. A new name is proposed for this taxon because it was impossible to ascribe to types of already described species in the group, deposited for more than 100 years in natural history institutions. The males have a dorsum showing deep and coarse punctations (absent in Rhipicephalus sanguineus sensu stricto) and adanal plates with large punctations (absent in R. sanguineus s.s.); the tail of the spiracular plate is as wide as the closest festoon (half the width in R. sanguineus s.s.). Females have large punctations in dorsal fields, a wide spiracular plate, and a "V" shaped genital opening; such a combination of characters cannot be found in other species of the group. Immatures are described from specimens collected on hosts (Rodentia and Eulipotyphla). Both larvae and nymphs are markedly smaller than R. sanguineus s.s. Nymphs display long, backward-projected auriculae; larvae are almost half the size of R. sanguineus s.s. The new species can hybridize with R. sanguineus s.s. in laboratory colonies producing an unfertile F2, laying brown and dry eggs that did not hatch. Phylogenetic analysis of partial coxI gene sequences placed R. hibericus in a well-supported clade with other sequences of R. sanguineus s.l. from Portugal, as a sister clade of R. sanguineus s.s. The new species does not belong to the R. turanicus group of species. Both 12S and 16S partial gene sequences were not as precise in the correct phylogenetic placement of R. hibericus, in part probably due to the existence of erroneously identified sequences in GenBank©. This description, together with the previous reinstatement of Rhipicephalus secundus and Rhipicephalus rutilus, and the description of the neotypes of R. sanguineus s.s. should help researchers to adequately identify their collections. Our findings demonstrate that R. turanicus is absent in southwestern Europe. Old collections should be re-examined to provide the actual range of the new species.

Hard ticks (Ixodida: Ixodidae) in the Colombian Caribbean harbor the Jingmen tick virus: an emerging arbovirus of public health concern.

BACKGROUND: Ticks are obligate hematophagous ectoparasites involved in transmitting viruses of public health importance. The objective of this work was to identify the Jingmen tick virus in hard ticks from the Colombian Caribbean, an arbovirus of importance for public health. METHODS: Ticks were collected in rural areas of Córdoba and Cesar, Colombia. Taxonomic identification of ticks was carried out, and pools of 13 individuals were formed. RNA extraction was performed. Library preparation was performed with the MGIEasy kit, and next-generation sequencing (NGS) with MGI equipment. Bioinformatic analyses and taxonomic assignments were performed using the Galaxy platform, and phylogenetic analyses were done using IQ-TREE2. RESULTS: A total of 766 ticks were collected, of which 87.33% (669/766) were Rhipicephalus microplus, 5.4% (42/766) Dermacentor nitens, 4.2% (32/766) Rhipicephalus linnaei, and 3.0% (23/766) Amblyomma dissimile. Complete and partial segments 1, 2, 3, and 4 of Jingmen tick virus (JMTV) were detected in the metatranscriptome of the species R. microplus, D. nitens, and A. dissimile. The JMTVs detected are phylogenetically related to JMTVs detected in Aedes albopictus in France, JMTVs detected in R. microplus in Trinidad and Tobago, JMTVs in R. microplus and A. variegatum in the French Antilles, and JMTVs detected in R. microplus in Colombia. Interestingly, our sequences clustered closely with JMTV detected in humans from Kosovo. CONCLUSIONS: JMTV was detected in R. microplus, D. nitens, and A. dissimile. JMTV could pose a risk to humans. Therefore, it is vital to establish epidemiological surveillance measures to better understand the possible role of JMTV in tropical diseases.

A new species of Rhipicephalus (Acari: Ixodidae), a parasite of giraffes in Kenya.

A new tick species belonging to the genus Rhipicephalus Koch, 1844 (Acari: Ixodidae), namely, Rhipicephalus walkerae n. sp., is described. The male and female of this species are similar to those of several species in the Rhipicephalus appendiculatus group but can be distinguished from them by the very dense pattern of medium-sized punctations covering the conscutum and scutum, long and narrow dorsal prolongation of the spiracular plate, and relatively short dorsal cornua; in addition, the male has long and narrow adanal plates without a posterolateral angle. R. walkerae is known only from Kenya, where the adults were collected from giraffes, Giraffa camelopardalis (L.).

A new species of Rhipicephalus (Acari: Ixodidae), a parasite of red river hogs and domestic pigs in the Democratic Republic of Congo.

A new tick species belonging to the genus Rhipicephalus Koch, 1844 (Acari: Ixodidae), namely, Rhipicephalus congolensis n. sp., is described. Males and females of this species are similar to those of Rhipicephalus complanatus Neumann, 1911 and Rhipicephalus planus Neumann, 1907, but it can be distinguished from them by a pattern of dense medium-sized punctations on the conscutum and scutum. Males of R. congolensis may be distinguished by the following characters: posterior half of the marginal groove deep with a sharp outer edge; anterior portion of the groove shallow with rounded edges; posteromedian groove distinct, long, and deep; adanal plates broadly sickle-shaped; bluntly pointed posteromedian spur on coxa I; and posterolateral spur on coxa I slightly longer or subequal to posteromedian spur. Females of R. congolensis may be distinguished by the following characters: outer edge of cervical grooves smooth and not clearly defined either by slope or punctations; genital aperture broad, bowl-shaped, and tripartite in appearance, with central flap flanked on either side by an oval depression; and posteromedian spur on coxa I tapering to its apex. R. congolensis is known only from the Democratic Republic of Congo, where the adults were collected from red river hogs, Potamochoerus porcus (L.), and domestic pigs, Sus scrofa (L.), within the dense equatorial forest in the districts of Equateur and Tshuapa, in the province of Equateur.

A new approach to characterization of the resistance of populations of Rhipicephalus microplus (Acari: Ixodidae) to organophosphate and pyrethroid in the state of Minas Gerais, Brazil.

The monitoring of resistance of cattle tick populations in Brazil to the chemical bases in use is largely limited to investigation of the phenotypic profile. There are few studies investigating the role played by the genotypic profile in acaricide resistance in the country. Therefore, the aim of the present study was to carry out molecular characterization and trace out the genetic profile of populations of Rhipicephalus microplus with respect to resistance to the organophosphate and pyrethroid chemical groups. For that purpose, larvae were genotyped belonging to 587 populations for pyrethroids and 306 for organophosphates, using the polymerase chain reaction technique. It was found that 75.49% and 97.44% of the larvae studied showed resistance to the organophosphates and pyrethroids, respectively. Among the populations resistant to pyrethroids, 91.9% were heterozygotes, showing that most of the resistant populations have only one allele responsible for resistance. Therefore, it is possible to conclude that the genotyped populations have high resistance to organophosphates, and even more so to pyrethroids. This information is fundamental for understanding the mechanisms of resistance of R. microplus to acaricides, to enable improvement of control techniques.

First record of the pantropical blue tick Rhipicephalus microplus in Namibia.

The invasive pantropical blue tick, Rhipicephalus microplus, has recently been collected from cattle in Namibia. A cross-sectional study aimed at recording the geographic distribution of Rhipicephalus decoloratus and establishing whether R. microplus is present in Namibia was conducted towards the end of summer (March-April) 2013. Ticks were collected from cattle on 18 privately owned farms across a large geographical scale. Ticks were collected from three to five cattle per farm and species belonging to the genera Hyalomma and Rhipicephalus were recovered. Rhipicephalus decoloratus was present on all farms and R. microplus was recorded on four of the farms. The small numbers of R. microplus compared to R. decoloratus collected in the mixed infestations, suggests that the introduction events were recent.

Cuticular fatty acid profile analysis of three Rhipicephalus tick species (Acari: Ixodidae).

Cuticular fatty acids (CFA) are important constituents of the arthropod exoskeleton, serving as structural and defense components, and participating in intra-species communication. Here we describe for the first time a comparative analysis of the CFA profiles of three tick species of the genus Rhipicephalus: R. annulatus, R. bursa and R. sanguineus. CFA profiles were determined for R. bursa and R. sanguineus grown both on rabbit or calf, and for R. annulatus grown on calf. CFA composition was compared for each species before and after ethanol treatment, for different hosts of each species, and between the different species. Our data suggest that adsorption of the host's fatty acids changes the apparent CFA composition. Ethanol treatment efficiently removed the unbound fatty acids from the ticks and revealed the actual composition. Comparison between ticks grown on rabbit versus calf showed significant difference in the relative abundance of fatty acids C14 and 9,12-C18:2 for R. bursa, and a difference in the relative abundance of C14 for R. sanguineus. Comparison of the CFA between the three species revealed significant differences in the abundance of fatty acids C16, 9,12-C18:2, 9-C18:1, C18 and C20. Our results show that while the host had a minor effect on CFA composition within each species, significant differences were observed in the CFA profiles of different species. We suggest that CFA profiles may be used to distinguish between related species. CFA analysis can also be used in studies of communication and defense mechanisms in ticks and other arthropods.