Comparison of resistance in three breeds of cattle against African ixodid ticks

Tick resistance in three breeds of cattle, two indigenous breeds (Arssi and Boran) and one Boran x Friesian cross-breed, were compared following natural tick infestations at Abernossa ranch in Ethiopia. The local Arssi breed was found to have the highest tick resistance, followed by the Boran breed, whereas the Boran x Friesian was the least resistant. Over a period of 12 months, from October 1991 to September 1992, a total of 32 897 ticks composed of four genera were collected from the animals. The four most abundant tick species were Amblyomma variegatum (61.7%), Boophilus decoloratus (16%); Rhipicephalus evertsi evertsi (16.3%) and Hyalomma marginatum rufipes (3.7%). Furthermore, 63.5% of all ticks were collected from cross-breed cattle, and 26.2% from the Boran, whereas the local Arssi breed carried only 10.3%. The results indicated that cattle resistant to one species of tick were also resistant to other tick species.     

Infestations of the bont tick Amblyomma hebraeum (Acari: Ixodidae) on different breeds of cattle in Zimbabwe

Infestations of adults and nymphs of Amblyomma hebraeum were counted on Brahman (Br), Brahman x Simmental (BS), Sanga (Sa) and Hereford (He) steers exposed to infested pastures at Mbizi in southern Zimbabwe in 1986–1987. Herefords were always the most heavily infested, while the Sanga tended to carry the fewest ticks with the Brahman and Brahman x Simmental groups being in between. The ratios of the engorged females on the four breeds were 2.3 : 1.4 : 1.4 : 1.0 for He : Br : BS : Sa. The ratios of the standard nymphs were 2.2 : 1.4 : 1.7 : 1.0 for He : Br : BS : Sa. The results confirm earlier observations in Africa and support the view that there are genetic differences between breeds in the expression of resistance to this tick species.Deceased.     

An update on the ecological distribution of Ixodid ticks infesting cattle in Rwanda: countrywide cross-sectional survey in the wet and the dry season

As part of the epidemiological studies aimed at developing an East Coast fever (ECF) immunisation control strategy, which combines an infection and treatment method with strategic tick control, a countrywide tick survey was carried out in both the dry and the wet season to determine the abundance and the dynamics of the tick populations infesting cattle in Rwanda. Six Ixodid tick species where identified from a total of 12,814 tick specimens collected. Rhipicephalus appendiculatus, the main vector of ECF was the most abundant (91.8%) followed by Boophilus decoloratus (6.1%) and Ambyomma variegatum (1.2%). Few ticks from the three other less economically important Ixodid species (Rhipicephalus compositus, R. evertsi evertsi and Ixodes cavipalpus) were recovered. Both adult and immature stages of the most dominant tick species were found to be widespread with a year round presence. The numbers of ticks were high in low land and medium zones and declined markedly in the higher regions of Rwanda. The geographical distribution of various tick species throughout the country and their epidemiological implications are discussed.     

Rhipicephalus appendiculatus feeding on rabbits and cattle: Salivary-gland responses to varying host resistance

AdultRhipicephalus appendiculatus ticks were fed as three sequential infestations on both rabbits and cattle. The feedings at first infestation on naive hosts were optimum for the ticks, whereas at third infestation the hosts were resistant, as expressed by reduced tick feeding performance. Ticks from naive and resistant hosts were examined for histological differences of salivary glands. In ticks fed on resistant rabbits there was a large increase in the synthesis of glycoprotein secretory granules in thec ₁ cells compared with ticks fed on naive rabbits. In ticks fed on naive and resistant cattle, the activity of thec ₁ cells was less than in ticks fed on naive and resistant rabbits. It was concluded that the salivary glands are able to respond selectively to conditions at the feeding site, and that this may be advantageous to the tick.     

Prevalence of hard tick infestations in cattle of Mizoram,India

The present study was conducted to determine the prevalence of hard tick infestations in cattle of Mizoram from April 2017 to March 2018. The prevalence of hard tick infestations was studied in relation to sex and age of animals and seasonal changes in a year. Cattle of selected places were examined carefully for the presence of ticks and in positive cases ticks were collected manually and identified on the basis of morphological characters. A total of 713 cattle were examined and out of which 452 (63.39%) cattle were found to be infested with hard ticks and the prevalent tick species was Rhipicephalus (Boophilus) microplus. A significantly (p < 0.01) higher infestation was observed in female cattle (66.43%) than males (48.83%). Age-wise highest prevalence of tick infestations was found in 1–5 years (73.41%) age group followed by >5 years age group (61.92%) and < 1 year (42.65%) age group, respectively. Seasonally, the prevalence of hard tick infestation was found highest (p < 0.01) in monsoon (77.91%) and lowest in winter (43.16%). The present study provides data on tick infestation in cattle of Mizoram, India.     

Prevalence of hard tick infestations in cattle of West Bengal,India

The present study was conducted to determine the prevalence of hard tick infestations in cattle of West Bengal from July 2015 to June 2016. The prevalence of hard tick infestations was studied in relation to sex and age of animals and seasonal changes in a year. Cattle of selected places were examined carefully for the presence of ticks and in positive cases ticks were collected manually and identified on the basis of morphological characters. A total of 310 cattle were examined and out of which, 130 (41.93%) cattle were found to be infested with hard ticks and the prevalent species were Rhipicephalus (Boophilus) sp., Hyalomma sp. and Haemaphysalis sp. of ticks. A significantly (p < 0.01) higher infestation was observed in female cattle (43.30%) than males (35.71%). Age-wise highest prevalence of tick infestations was found in <1 year (65%) age group followed by >3 years age group (36.8%) and 1–3 years (35.63%) age group, respectively. Seasonally, the prevalence of hard ticks was highest (p < 0.01) in monsoon (59.25%) and lowest in winter (27.09%). The study revealed that the prevalence of Rhipicephalus (Boophilus) sp. (32.25%) was significantly (p < 0.01) higher compared to Hyalomma (12.58%) and Haemaphysalis sp. (3.22%). The observations of the present study would provide a basis for evolving effective control strategy for the management of ticks in bovines of West Bengal.     

Hard tick species (Acari: Ixodidae) and infestation in two livestock agroecosystems from Antioquia,Colombia

Tick infestation affects about 80% of livestock globally while transmitting various pathogens causing high economic losses. This study aimed to determine the degree of tick infestation in two regions, North and Middle Magdalena in Antioquia, Colombia, to identify the ixodid tick species found and the associated risk factors. A cross-sectional study was carried out in 48 farms distributed in six municipalities of Antioquia. Two paddocks and eight bovines per farm were evaluated to estimate tick infestation (adults, nymphs, and larvae). Tick species were identified through a morphological and molecular analysis based on partial sequences of data obtained from DNA molecular markers, two mitochondrial (16S rRNA and COI), and one genomic DNA gene (18S rRNA). A multivariate Poisson regression model was applied to estimate the associated risk factors with ticks in cattle. Rhipicephalus microplus, Amblyomma patinoi and Dermacentor nitens were present in the livestock agroecosystems in the Middle Magdalena region; the highest incidence of tick infestation in cows and paddocks was reported in the municipality of Puerto Triunfo. The livestock agroecosystems in Middle Magdalena were characterized by a higher presence of adult R. microplus in cattle. Larval infestation of R. microplus, followed by D. nitens, was also found in paddocks. The multivariate analysis showed that the origin of cattle was the main risk factor associated with the presence of ticks (i.e., when cattle came from outside the farm). Cattle movement between farms in Middle Magdalena can contribute to the spread of ticks in this region.

     

The effects of the brown ear-tick, Rhipicephalus appendiculatus, on milk production of Sanga cattle

Abstract. Lactating Sanga cows of the Mashona breed from Zimbabwe, receiving either a low or a high level of nutritional supplement, were exposed to two levels of infestation of adults of the brown ear-tick, Rhipicephalus appendiculatus in the highveld of Zimbabwe. The effect of the ticks on the milk yield was measured over an 11-week period during the rainy season from January to April 1986. A technique in which calves were weighed before and after suckling was used to estimate milk yield. There were significant treatment effects of ticks (P < 0.05) on milk production but no significant differences in liveweight gain between calves from tick-free and tick-infested dams. The loss in milk production was poorly related to the number of female ticks that engorged, being 9 g (SEM 4) per tick. A Friesian x Hereford (Bos taurus) reference group of cattle carried 50% more ticks than the Mashona cows, illustrating a difference in resistance between the breeds. Thirteen screw-worm (Chrysomya bezziana) strikes were recorded amongst the thirty-two Mashona cows compared with twenty-one amongst the ten Friesian × Hereford animals between January and the end of March.     

Ticks and Tick-Borne Diseases of Livestock Belonging to Resource-poor Farmers in the Eastern Free State of South Africa

The paper provides a summary of three studies conducted in the eastern Free State of South Africa between 1998 and 2000. In a questionnaire-based study approximately 21% of interviewed resource-poor farmers (n = 150) indicated that they experienced problems with ticks and tick-borne diseases. About 56% of farmers indicated that tick-related problems were most severe in summer, while 32% indicated that the most problems were encountered in winter. About 12% indicated that the tick problems were experienced throughout the year. Farmers also indicated that the highest tick burdens were experienced between spring and early winter. The principal ticks infesting cattle (n = 30) were found to be Boophilus decoloratus (53.1%), Rhipicephalus evertsi evertsi (44.7%), Rhipicephalus follis (1.0%), Rhipicephalus gertrudae (0.7%) and Rhipicephalus warburtoni (0.4%). On small stock (n = 188), R. evertsi evertsi (68%) and B. decoloratus (32%) were recorded as the main ticks in the study area. A sero-epidemiological survey of cattle (n = 386) showed that 94% of cattle were sero-positive for Babesia bigemina by IFAT, while 87% were sero-positive for Anaplasma by indirect ELISA. All the animals were sero-negative for Babesia bovis and this is probably because the tick vector, Boophilus microplus, is not present in the study area. All sheep and goats were sero-positive for Theileria species by IFAT while 85% of sheep and 100% of goats tested positive for Anaplasma species by competition inhibition ELISA. The high incidence of positive serological results for B. bigemina and Anaplasma in cattle, and Theileria and Anaplasma in sheep and goats and the absence of clinical cases would indicate that this area is endemically stable for these diseases. This revised version was published online in July 2006 with corrections to the Cover Date.     

Resistant ticks inhibit Metarhizium infection prior to haemocoel invasion by reducing fungal viability on the cuticle surface

We studied disease progression of, and host responses to, four species in the Metarhizium anisopliae complex expressing green fluorescent protein (GFP). We compared development and determined their relative levels of virulence against two susceptible arthropods, the cattle tick Rhipicephalus annulatus and the lepidopteran Galleria mellonella, and two resistant ticks, Hyalomma excavatum and Rhipicephalus sanguineus. Metarhizium brunneum Ma7 caused the greatest mortality of R. annulatus, Metarhizium robertsii ARSEF 2575 and Metarhizium pingshaense PPRC51 exhibited intermediate levels of virulence, and Metarhizium majus PPRC27 caused low mortality of cattle ticks. Conidia of all four species germinated on all hosts examined, but on resistant hosts, sustained hyphal growth was inhibited and GFP emission steadily and significantly decreased over time, suggesting a loss of fungal viability. Cuticle penetration was observed only for the three most virulent species infecting susceptible hosts. Cuticles of resistant and susceptible engorged female ticks showed significant increases in red autofluorescence at sites immediately under fungal hyphae. This is the first report (i) of tick mortality occurring after cuticle penetration but prior to haemocoel colonization and (ii) that resistant ticks do not support development of Metarhizium germlings on the outer surface of the cuticle. Whether reduced Metarhizium viability on resistant tick cuticles is due to antibiosis or limited nutrient availability is unknown.     

Tick-susceptible Bos taurus cattle display an increased cellular response at the site of larval Rhipicephalus (Boophilus) microplus attachment, compared with tick-resistant Bos indicus cattle

Cattle demonstrate divergent and heritable phenotypes of resistance and susceptibility to infestation with the cattle tick Rhipicephalus (Boophilus) microplus. Bos indicus cattle are generally more resistant to tick infestation than Bos taurus breeds although large variations in resistance can occur within subspecies and within breed. Increased tick resistance has been previously associated with an intense hypersensitivity response in B. taurus breeds; however, the mechanism by which highly resistant B. indicus cattle acquire and sustain high levels of tick resistance remains to be elucidated. Using the commercially available Affymetrix microarray gene expression platform, together with histological examination of the larval attachment site, this study aimed to describe those processes responsible for high levels of tick resistance in Brahman (B. indicus) cattle that differ from those in low-resistance Holstein-Friesian (B. taurus) cattle. We found that genes involved in inflammatory processes and immune responsiveness to infestation by ticks, although up-regulated in tick-infested Holstein-Friesian cattle, were not up-regulated in Brahman cattle. In contrast, genes encoding constituents of the extracellular matrix were up-regulated in Brahmans. Furthermore, the susceptible Holstein-Friesian animals displayed a much greater cellular inflammatory response at the site of larval R. microplus attachment compared with the tick-resistant Brahman cattle.     

New foci of <Emphasis Type="Italic">Rhipicephalus microplus</Emphasis> in West Africa

The invasive character of Rhipicephalus microplus was observed in Benin, the second West-African country from which this ticks species has been collected after the initial confirmed record in Ivory Coast in 2007. A cross-sectional study was carried out in the Department of Mono to examine the presence of the tick R. microplus. The survey covered 9 herds (villages) in an agro-ecological zone inhabited by agro-pastoralists, including the State Farm of Kpinnou that imported Girolando cattle from Brazil. Almost 800 ticks were sampled from 36 cattle, on average four cattle per village. The morphological identification revealed ticks of two different genera: Rhipicephalus and Amblyomma. Rhipicephalus microplus was the only representative of the species previously known as Boophilus or blue ticks. Its taxonomic identity was confirmed molecularly by PCR–RFLP. A comparison was made with the situation of R. microplus in Brazil.     

Efficacy of pheromone-acaricide-impregnated tail-tag decoys for controlling the bont tick,Amblyomma hebraeum (Acari: Ixodidae), on cattle in Zimbabwe

A large-scale field test using pheromone-acaricide-impregnated plastic tail-tag decoys demonstrated excellent efficacy of these devices for control of the bont tick,Amblyomma hebraeum, on cattle in Zimbabwe. The tail tags were impregnated with a mixture containingo-nitrophenol, methyl salicylate, 2,6-dichlorophenol and phenylacetaldehyde and one of three different acaricides (cyfluthrin, flumethrin or alphacypermethrin).o-Nitrophenol and methyl salicylate are components of theA. hebraeum attraction-aggregation-attachment pheromone, while 2,6-dichlorophenol and phenylacetaldehyde are proven attractants for this tick. Botho-nitrophenol and methyl salicylate were lost gradually from the tags over 12 and 14 week periods, respectively. In field trials, tick counts were compared between cattle that received tail tags either impregnated with pheromone mixture alone, cyfluthrin and pheromone mixture, flumethrin and pheromone mixture, alphacypermethrin and pheromone mixture or were left untreated. During the first 3 month trial period, control of adult bont ticks was 94.9% with cyfluthrin tail tags and 87.5% with flumethrin tail tags. In general, there was no significant difference in bont tick numbers on cattle without tags and those with tail tags containing pheromone only. When the trial was repeated for another 3 month period, control of bont ticks with tail tags containing cyfluthrin and flumethrin was 99.3 and 95.1%, respectively. However, control of bont ticks using alphacypermethrin was only 79.2%. Overall, retention of tail tags was excellent although some loss was encountered during the rainy season. In addition to controlling bont ticks, the tail tags provided moderate control of other tick species (Rhipicephalus evertsi evertsi, Rhipicephalus zambeziensis andHyalomma spp.) simultaneously infesting cattle in the trials.Deceased.     

Immunisation of rabbits against the brown ear tick,Rhipicephalus appendiculatus using tick haemolymph

Tick naive rabbits were immunised with haemolymph components from partially fed Rhipicephalus appendiculatus adult ticks and subsequently challenged with all the developmental instars of the tick. The results obtained showed that the rabbits were rendered resistant to all the instars of the tick. However, the resistance was more pronounced in adult ticks than in the immature stages. The resistance was manifested as a reduction in the number of ticks that fed successfully to engorgement, reduced engorgement weights and reduced fecundities. Re challenging the resistant experimental rabbits with all the developmental instar stages of Rhipicephalus appendiculatus showed that resistance was maintained in subsequent infestations.     

Staphylococcus saprophyticus is a pathogen of the cattle tick Rhipicephalus (Boophilus) microplus

During experimental Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) infestation on cattle, approximately 5% of engorged female ticks showed symptoms of bacterial infection. The affected ticks were unable to oviposit, secreted a distinctive yellow exudate through the genital orifice and eventually died. Microscopic analysis of tick exudate showed abundant clusters of Gram-positive cocci bacteria that were isolated and cultured on bacteriological medium. Biochemical phenotyping and 16S rRNA ribotyping analysis on cultured bacteria identified it as Staphylococcus saprophyticus. This species was also isolated from healthy tick larvae, indicating that S. saprophyticus is commonly found in ticks during different developmental stages. However, conspicuous symptoms are only found on fully engorged females. Cultured S. saprophyticus induced identical pathological symptoms when the bacteria were experimentally inoculated into healthy ticks, demonstrating it to be the causative agent of the R. microplus infectious lethal disease described in this work.     

Ixodid ticks (Acari: Ixodidae) infesting humans in Tokat Province of Turkey: species diversity and seasonal activity

Ixodid ticks (Acari: Ixodidae) are the major vectors of pathogens threatening animal and human health. Tokat Province, Turkey, is a suitable habitat for extended tick activity with its moderate climate and vegetation. In the present study, we surveyed humans visiting health centers to determine the species diversity, geographical distribution, and seasonal activity of ixodid ticks infesting them. Out of 5,999 adult ticks collected from humans from April to September, 2008, 800 ticks were identified to species, while the remaining were identified to genus according to their distinct morphological characteristics. Hyalomma marginatum, Hyalomma detritum, Rhipicephalus bursa, Rhipicephalus (Boophilus) annulatus, Haemaphysalis punctata, Dermacentor marginatus, and Ixodes laguri were the most prevalent tick species among 24 ixodid tick species infesting humans in the region. One of these tick species, Hyalomma isacii was identified as a new record for the ixodid tick fauna of Turkey. Hyalomma species were the most abundant in summer, while Dermacentor and Ixodes species displayed the lowest frequency. Hyalomma aegyptium infestation was very common on humans in the province. Results indicated that a variety of ixodid tick species infest humans depending on the season in the target area. It is possible that a variety of ixodid tick species may contribute to the spread of tick‐borne diseases such as Crimean‐Congo haemorrhagic fever virus (CCHFV), which is endemic in the region.     

Resistance of indigenous African cattle to the tickAmblyomma hebraeum

Field collections ofAmblyomma hebraeum Koch adults from six breeds of cattle were conducted on two farms in the Northern Transvaal. The density ofA. hebraeum adults was highest on Simmentaler cows, followed by Santa gertrudis, Africaner, Bonsmara, Brahman and Nguni. Indigenous breeds, namely Nguni, Bonsmara and Africaner, have the highest level of resistance toA. hebraeum. The relationship between tick abundance and the high level of resistance found in the indigenous breeds is discussed.     

Resistance in cattle againstRhipicephalus appendiculatus with an assessment of cross-resistance toR. pulchellus (Acari: Ixodidae)

A comparison of the yield of engorged nymphs ofRhipicephalus appendiculatus andR. pulchellus was carried out between cattle highly resistant toR. appendiculatus but susceptible toR. pulchellus, and cattle and rabbits susceptible to both species.Resistant cattle yielded fewer and smallerR. appendiculatus nymphs than either susceptible cattle or rabbits. More nymphs of both tick species dropped from susceptible cattle but no differences were detected in the mean weight of engorgedR. pulchellus nymphs fed onR. appendiculatus-resistant and susceptible cattle, although resistant animals yielded more nymphs ofR. pulchellus than ofR. appendiculatus.An acute inflammatory reaction, accompanied by intense pruritus and grooming, was observed in the ears of the resistant cattle infested withR. appendiculatus, but no reaction was detected in the opposite ears whereR. pulchellus was feeding.The low cross-resistance between these two closely related tick species suggests that different antigens may be involved in the development of resistance in cattle to different tick species.     

Role of cuticular lipids and water-soluble compounds in tick susceptibility to Metarhizium infection

The arthropod cuticle acts as a physiochemical barrier protecting the organism from pathogens' entry. Entomopathogenic fungi actively penetrate the cuticles of arthropod hosts and are therefore directly affected by cuticle composition. Previously we have observed that Metarhizium spp. developing on resistant ticks ultimately die without penetrating tick's cuticle, suggesting that the cuticles of resistant ticks have antifungal compounds. In the present study, lipids and water-soluble cuticular components were extracted from engorged female tick cuticles, of one susceptible and one resistant tick species to Metarhizium spp. While conidia exposed to lipids from the susceptible tick, Rhipicephalus annulatus, germinated and differentiated into appressorium, conidia exposed to lipids from the resistant tick, Hyalomma excavatum, were inhibited. Soluble cuticular component extracts from both susceptible and resistant ticks stimulated conidial germination but not appressorium differentiation. A comparative analysis of the fatty acid profile in lipid extract of each tick exhibited similar compositions, but the relative abundance of C16:0, C18:0, C18:1ω9C and C20:0 was 2–5 times higher in the extracts from resistant ticks. All of these fatty acids inhibited conidial germination in vitro at 1% and 0.1% w/v concentration, but C20:0 stimulated appressorium differentiation at low concentration. This is the first report demonstrating a possible link between the presence of antifungal compounds in a specific concentration in tick cuticle and tick resistance to infection.     

Monthly dynamics of ticks (Acari: Ixodida) infesting N'Dama cattle in the Republic of Guinea

The occurrence of ixodid ticks on N'Dama cattle was studied in the Republic of Guinea between June 1994 and May 1995. Monthly tick collections were performed on 80 animals from 14 villages located in Dabola, Kouroussa and Dinguiraye prefectures. A total of 19,804 ticks was collected and classified using standard taxonomic keys. The following tick species were identified: Amblyomma variegatum, Hyalomma marginatum rufipes, Hyalomma trunctum, Hyalomma nitidum, Rhipicephalus lunulatus, Rhipicephalus muhsamae, Rhipicephalus senegalensis, Rhipicephalus sulcatus, Rhipicephalus turanicus, Boophilus annulatus, Boophilus geigyi. Boophilus spp. were the most numerous adult ticks (57.1%), Am. variegatum adults constituted 27.4%, while 12.4% were Rhipicephalus spp. and 2.5% Hyalomma spp. Rhipicephalus turanicus and Hyalomma nitidum were recorded for the first time in the country. Am. variegatum and Boophilus spp. were present throughout the year, whereas Am. variegatum adults showed a peak during the rainy season between April and September. Immature stages collected belonged exclusively to the genera Amblyomma and Boophilus. Am. variegatum larvae and nymphs showed a peak during the dry season (October-March); no significant variation between seasons was observed for Boophilus immatures. A significantly higher infestation of cattle by Rhipicephalus spp. was found in Dabola and Kouroussa prefectures, located in the southern part of the study area, with similar climatic, vegetation and rainfall characteristics. Possible options for the control of ticks in the study area are briefly discussed.