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Ticks cause substantial production losses for beef and dairy cattle. Cattle resistance to ticks is one of the most important factors affecting tick control, but largely neglected due to the challenge of phenotyping. In this study, we evaluate the pooling of tick resistance phenotyped reference populations from multi-country beef cattle breeds to assess the possibility of improving host resistance through multi-trait genomic selection. Data consisted of tick counts or scores assessing the number of female ticks at least 4.5 mm length and derived from seven populations, with breed, country, number of records and genotyped/phenotyped animals being respectively: Angus (AN), Brazil, 2,263, 921/1,156, Hereford (HH), Brazil, 6,615, 1,910/2,802, Brangus (BN), Brazil, 2,441, 851/851, Braford (BO), Brazil, 9,523, 3,062/4,095, Tropical Composite (TC), Australia, 229, 229/229, Brahman (BR), Australia, 675, 675/675, and Nguni (NG), South Africa, 490, 490/490. All populations were genotyped using medium density Illumina SNP BeadChips and imputed to a common high-density panel of 332,468 markers. The mean linkage disequilibrium (LD) between adjacent SNPs varied from 0.24 to 0.37 across populations and so was sufficient to allow genomic breeding values (GEBV) prediction. Correlations of LD phase between breeds were higher between composites and their founder breeds (0.81 to 0.95) and lower between NG and the other breeds (0.27 and 0.35). There was wide range of estimated heritability (0.05 and 0.42) and genetic correlation (-0.01 and 0.87) for tick resistance across the studied populations, with the largest genetic correlation observed between BN and BO. Predictive ability was improved under the old-young validation for three of the seven populations using a multi-trait approach compared to a single trait within-population prediction, while whole and partial data GEBV correlations increased in all cases, with relative improvements ranging from 3% for BO to 64% for TC. Moreover, the multi-trait analysis was useful to correct typical over-dispersion of the GEBV. Results from this study indicate that a joint genomic evaluation of AN, HH, BN, BO and BR can be readily implemented to improve tick resistance of these populations using selection on GEBV. For NG and TC additional phenotyping will be required to obtain accurate GEBV., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Cardoso, Matika, Djikeng, Mapholi, Burrow, Yokoo, Campos, Gulias-Gomes, Riggio, Pong-Wong, Engle, Porto-Neto, Maiwashe and Hayes.)

Background: Ticks and tick-borne diseases are a major impediment to livestock production worldwide. Cattle trade and transnational transhumance create risks for the spread of ticks and tick-borne diseases and threaten cattle production in the absence of an effective tick control program. Few studies have been undertaken on cattle ticks in the Central African region; therefore, the need to assess the occurrence and the spatial distribution of tick vectors with the aim of establishing a baseline for monitoring future spread of tick borne-diseases in the region is urgent., Results: A total of 7091 ixodid ticks were collected during a countrywide cross-sectional field survey and identified using morphological criteria. Of these, 4210 (59.4%) ticks were Amblyomma variegatum, 1112 (15.6%) Rhipicephalus (Boophilus) microplus, 708 (10.0%) Rhipicephalus (Boophilus) decoloratus, 28 (0.4%) Rhipicephalus (Boophilus) annulatus, 210 (3.0%) Hyalomma rufipes, 768 (10.8%) Hyalomma truncatum, and 19 (0.3%) Rhipicephalus sanguineus. Three ticks of the genus Hyalomma spp. and 33 of the genus Rhipicephalus spp. were not identified to the species level. Cytochrome c oxidase subunit 1 (cox1) gene sequencing supported the data from morphological examination and led to identification of three additional species, namely Hyalomma dromedarii, Rhipicephalus sulcatus and Rhipicephalus pusillus. The finding of the invasive tick species R. microplus in such large numbers and the apparent displacement of the indigenous R. decoloratus is highly significant since R. microplus is a highly efficient vector of Babesia bovis., Conclusions: This study reports the occurrence and current geographical distribution of important tick vectors associated with cattle in Cameroon. It appears that R. microplus is now well established and may be displacing native Rhipicephalus (Boophilus) species, such as R. decoloratus. This calls for an urgent response to safeguard the livestock sector in western central Africa.

Background and Aim: Climatic conditions significantly impact the life stages and distribution patterns of ticks and tickborne diseases. South Africa's central plateau and various biomes offer a distinct landscape for studying the geography's effects. The study estimated tick species prevalence and the influential factors on their survival. Materials and Methods: Ticks were gathered from communal cattle in South African provinces including Limpopo (LP), Gauteng (GP), Mpumalanga (MP), KwaZulu-Natal (KZN), the Eastern Cape (EC), and the Free State (FS), from September 2020 to November 2022. Using data from South African weathercasts, the annual climate was assessed. Results: A total of 3,409 ticks were collected, with the highest infestation observed in KZN (45%), followed by LP (26%), EC (19%), GP (5%), MP (2%), and the FS (2%). The most prevalent tick species were Amblyomma hebraeum (55.1%), Rhipicephalus evertsi evertsi (13.9%) and Rhipicephalus (Boophilus), and decoloratus (11.9%). Other species included R. (Boophilus) microplus (10.85%), Hyalomma marginatum (4.8%), Rhipicephalus appendiculatus (1.4%), Harpalus rufipes (0.8%), Rhipicephalus exophthalmos (0.2%), Rhipicephalus glabroscutatus (0.2%), Rhipicephalus sanguineus (0.2%), Haemaphysalis silacea (0.5%), Ixodes pilosus (0.1%), and Rhipicephalus simus (0.1%). The infestations were most prevalent on farms in Pongola and KZN. The temperature fluctuated between 12°C and 35°C during data gathering, while humidity varied between 40% and 65%. Conclusion: This study showed that ticks survive optimally in warm temperatures and high humidity conditions. Livestock farms with high tick infestations may be associated with several risk factors. These practices could involve suboptimal grazing, insufficient acaricidal treatment, and detrimental effects resulting from traditional animal husbandry. Future research is needed to longitudinally evaluate the effects of climate change on tick populations, pathogen transmission, hosts, habitats, and human behavior, influencing potential exposure risks. [ABSTRACT FROM AUTHOR]

Ticks are amongst the important ectoparasites where livestock are concerned, as they adversely affect the animals through bloodsucking. In tropical and subtropical countries, they transmit pathogens such as babesiosis, theileriosis, ehrlichiosis, and anaplasmosis in cattle, causing a reduction in production rate and significant concomitant economic losses. Ticks affect 80% of the cattle population across the world, with an estimated economic loss of USD 20–30 billion per year. In South Africa, economic losses in the livestock industry caused by ticks and tick-borne diseases are estimated to exceed USD 33 million per year (ZAR 500 million). There are seven major genera of ixodid ticks in Southern Africa (i.e., Amblyomma, Dermacentor, Haemaphysalis, Hyalomma, Ixodes and Rhipicephalus). The environment in which a tick lives is made up of all the various biological and abiotic factors that are either necessary or unnecessary for its life. The areas where various ticks have been found have been documented in many publications. Using these data, maps of possible species' habitats can be made. Historical records on tick distribution may be incorrect due to identification mistakes or a change in the tick's name. All the sources used to generate the maps for this review were unpublished and came from a wide range of sources. To identify tick species and the accompanying microbial ecosystems, researchers are increasingly adopting tick identification methods including 16S and 18S rDNA gene sequencing. Indeed, little is known about the genetic alterations that give important traits, including the predilection for tick hosts, transmission, and acaricide resistance. Opportunities for exploring these changes in tick populations and subpopulations are provided by advancements in omics technologies. The literature on the variety of ixodid ticks, their direct and indirect effects, and control methods in South Africa is compiled in this review. [ABSTRACT FROM AUTHOR]

Background: The ixodid tick Rhipicephalus appendiculatus is the main vector of Theileria parva, wich causes the highly fatal cattle disease East Coast fever (ECF) in sub-Saharan Africa. Rhipicephalus appendiculatus populations differ in their ecology, diapause behaviour and vector competence. Thus, their expansion in new areas may change the genetic structure and consequently affect the vector-pathogen system and disease outcomes. In this study we investigated the genetic distribution of R. appendiculatus across agro-ecological zones (AEZs) in the African Great Lakes region to better understand the epidemiology of ECF and elucidate R. appendiculatus evolutionary history and biogeographical colonization in Africa. Methods: Sequencing was performed on two mitochondrial genes (cox1 and 12S rRNA) of 218 ticks collected from cattle across six AEZs along an altitudinal gradient in the Democratic Republic of Congo, Rwanda, Burundi and Tanzania. Phylogenetic relationships between tick populations were determined and evolutionary population dynamics models were assessed by mismach distribution. Results: Population genetic analysis yielded 22 cox1 and 9 12S haplotypes in a total of 209 and 126 nucleotide sequences, respectively. Phylogenetic algorithms grouped these haplotypes for both genes into two major clades (lineages A and B). We observed significant genetic variation segregating the two lineages and low structure among populations with high degree of migration. The observed high gene flow indicates population admixture between AEZs. However, reduced number of migrants was observed between lowlands and highlands. Mismatch analysis detected a signature of rapid demographic and range expansion of lineage A. The star-like pattern of isolated and published haplotypes indicates that the two lineages evolve independently and have been subjected to expansion across Africa. Conclusions: Two sympatric R. appendiculatus lineages occur in the Great Lakes region. Lineage A, the most diverse and ubiquitous, has experienced rapid population growth and range expansion in all AEZs probably through cattle movement, whereas lineage B, the less abundant, has probably established a founder population from recent colonization events and its occurrence decreases with altitude. These two lineages are sympatric in central and eastern Africa and allopatric in southern Africa. The observed colonization pattern may strongly affect the transmission system and may explain ECF endemic instability in the tick distribution fringes. [ABSTRACT FROM AUTHOR]

About 80% of the world's cattle are affected by ticks and tick-borne diseases, both of which cause significant production losses. Cattle host resistance to ticks is the most important factor affecting the economics of tick control, but it is largely neglected in tick-control programs due to technical difficulties and costs associated with identifying individual-animal variation in resistance. The present paper reviews the scientific literature to identify factors affecting resistance of cattle to ticks and the biological mechanisms of host tick resistance, to develop alternative phenotype(s) for tick resistance. If new cost-effective phenotype(s) can be developed and validated, then tick resistance of cattle could be genetically improved using genomic selection, and incorporated into breeding objectives to simultaneously improve cattle productive attributes and tick resistance. The phenotype(s) could also be used to improve tick control by using cattle management. On the basis of the present review, it is recommended that three possible phenotypes (haemolytic analysis; measures of skin hypersensitivity reactions; simplified artificial tick infestations) be further developed to determine their practical feasibility for consistently, cost-effectively and reliably measuring cattle tick resistance in thousands of individual animals in commercial and smallholder farmer herds in tropical and subtropical areas globally. During evaluation of these potential new phenotypes, additional measurements should be included to determine the possibility of developing a volatile-based resistance phenotype, to simultaneously improve cattle resistance to both ticks and biting flies. Because the current measurements of volatile chemistry do not satisfy the requirements of a simple, cost-effective phenotype for use in commercial cattle herds, consideration should also be given to inclusion of potentially simpler measures to enable indirect genetic selection for volatile-based resistance to ticks. About 80% of the world's cattle are affected by ticks and tick-borne diseases, with estimated economic losses from ticks ranging from US$20 to US$30 billion per year. Cattle host resistance is the most important factor affecting the economics of tick control, but it is largely absent in tick-control programs due to the difficulties and expense of identifying host tick resistance. The present paper reviews the literature to identify factors affecting resistance of cattle to ticks, so as to develop cost-effective ways of measuring tick resistance in cattle. The review recommends that three possible methods (haemolytic analysis; skin hypersensitivity reactions; simplified artificial tick infestations) be further developed to consistently, cost-effectively and reliably measuring cattle tick resistance. [ABSTRACT FROM AUTHOR]