Attractivity of cattle infested by Amblyomma variegatum (Acari: Ixodidae) for conspecific adult ticks from the field in Guadeloupe

Four field experiments were conducted with creole cattle in Guadeloupe to study the attractivity for adult ticks of animals previously infested with males of Amblyomma variegatum producing aggregation attachment pheromones (AAPs). In each experiment, two groups of cattle were used; the first group was infested with adult A. variegatum and the second group was kept free of ticks and pheromones by acaricidal treatment and by washing the hair and skin of previously infested sites. Both groups were then exposed to natural infestation by ticks present in the environment or by ticks bred in the laboratory and released on the pasture. The number of additional ticks infesting animals were compared between the treated and control groups. There were no significant differences between both groups in the numbers of new male ticks infesting the animals during the first days following the beginning of the experiment. Thereafter, comparison of the slopes of infestation indicated that infested cattle were no more attractive for male ticks than uninfested hosts. Uninfested cattle were spontaneously and rapidly infested by male ticks. It is concluded that carbon dioxide or another host component was a major attractant for A. variegatum males. Female ticks attached on predilection sites exclusively in the presence of AAP-producing males, i.e. 5–10 days after the attachment of the first males. Based on these results we postulate that slow-release devices impregnated with pheromones have no additional attractive effect on A. variegatum males under Caribbean conditions. However, they may be useful in inducing the attachment of females, but only in the first days preceding the arrival of pioneer AAP-producing males. © Rapid Science Ltd. 1998     

Footbath acaricide treatment to control cattle infestation by the tick Amblyomma variegatum

Previous studies have shown that about 90% of adult Amblyomma variegatum Fabricius (Acari: Ixodidae) picked up daily by grazing cattle are still attached to the interdigital areas in the evening, when the animals return from pasture. It was therefore postulated that a targeted treatment, designed to kill the ticks attached to the feet, would limit infestation of the predilection sites. Footbaths filled with various pyrethroid formulations were used over 3 years, at the beginning of the rainy season (from mid-May to the end of July), to assess the efficacy of such a control method. It proved efficient in preventing the ticks from attaching to the predilection sites. Although five to 12 A. variegatum adults attached to each treated animal daily, and although the tick burden of the predilection sites of control cattle increased each day by four to 10 ticks, the average infestation of the predilection sites of treated cattle that were initially highly infested (over 100 ticks/animal) continuously decreased to reach a level of about 10-30 ticks/animal after 6-8 weeks of treatment. In herds with a lower initial tick burden (40-70 ticks/animal) this level was obtained within 2-3 weeks and the mean infestation subsequently remained consistently low. Footbath treatment carried out every other day during the adult peak infestation period should therefore greatly limit losses due to ticks. This method was appreciated by traditional livestock farmers, essentially because it is not time-consuming and because it requires only c. 200 mL aqueous formulation per animal at each passage. The cost of the acaricide needed to treat one animal during the peak infestation period was assessed at c. euro 0.20. This control method might also have an impact on some species of tsetse flies and mosquitoes, thereby contributing to trypanosomiasis and malaria control.     

Attachment kinetics of the adult tick Amblyomma variegatum to cattle

At the beginning of the 1999 rainy season, three traditional cattle herds were monitored for 48 days while grazing in the bushy savannah of southwestern Burkina Faso. Cattle in each herd were caught on several occasions each day and the attached ticks were counted. This confirmed that Amblyomma variegatum Fabricius (Acari: Ixodidae) adults picked up in the pastures mainly attach to the interdigital areas (87% of the 791 ticks captured), and reach the predilection sites later (chest and udder/inguinal area) when the animals lie down. As many females as males attached to the hosts, but the seasonal distribution was very heterogeneous, with only a few females attaching as long as the humidity rate remained low. It is suggested that this prevents eggs from being laid when conditions are not optimal for their survival and that of the larvae. Ticks attached all day but the number picked up hourly and daily varied greatly according to their density on the pasture. As a general trend, confirmed by another study carried out in 2005, the number of ticks picked up daily increased from less than one tick/animal/day, before the onset of the rainy season, to 6.5 (+/- 1.5) ticks/animal/day on average during the infestation peak, which lasted 6-8 weeks, until early or mid-July. The number then decreased to less than one tick/animal/day from the end of July onwards. The infestation on the predilection sites followed the same trend, with a daily tick burden increase of three to five A. variegatum adults, depending on herd and year, during the infestation peak.     

Chorioptic Mange (Acarina: Psoroptidae) in Domestic and Wild Ruminants in Israel

In a 20-year-survey, 9364 dairy cattle in 324 herds kept under a zero-grazing management, 1252 beef cattle in 46 herds grazing all the year round, 3347 sheep in 134 herds (only 26 are grazing herds), and 872 goats in 47 herds (only 20 are grazing) were examined. The mites collected from cattle were identified as Chorioptes texanus only, and those from sheep, goats and gazelles were identified as C. bovis. Chorioptic mange was not diagnozed in grazing beef cattle, ibexes and housed animals (as compared to grazing herds), and in rams and billy goats. Holstein-Israeli bulls kept in insemination centres were not clinically infested, whereas four Charolais bulls were infested with chorioptic mange. Infestation rate was higher in older animals than in younger ones. Hoggets and young goats over 10 months and heifers over 13 months were found clinically infested with Choriopic mites. Lesions were not usually extensive and occurred mainly in predilection sites. The ocular form in sheep and the groin form in goats are very uncommon and apparently are reported for the first time. Chorioptic mange was recorded generally throughout the year. In our study seasonal distribution could not be demonstrated in cattle, while in sheep and goats the highest infestation rate occurred in February to March and the lowest in August and September.     

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.     

The impact of Ixodiphagus hookeri, a tick parasitoid, on Ambl yomma variegatum (Acari: Ixodidae) in a field trial in Kenya

In an experiment to investigate the effect of the tick parasitoid, Ixodiphagus hookeri, on tick numbers on cattle, 150 000 parasitoids were released over a period of 1 year in a field where ten cattle infested with multiple tick species were kept. Amblyomma variegatum was reduced from 44 to two ticks per animal while Rhipicephalus appendiculatus increased over the time of parasitoid release. During the time of release 51% of the nymphs of A. variegatum collected from the animals were parasitized. The recovery of the parasitoids after the releases were stopped was only 9%. The total numbers of A. variegatum remained low up to 1 year after the parasitoid release was stopped. This study gives an insight into how I. hookeri could be used strategically for the management of A. variegatum on small-scale farms.     

Tick infestation of dogs in Thessaloniki,northern Greece

Ticks were collected from 249 dogs, admitted over a one-year period (1996-1997) to a Veterinary Teaching Hospital and four private veterinary practices located in the county of Thessaloniki, Greece. A total of 2812 ticks (Acari: Ixodidae) were collected, of which 2511 (89.3%) were Rhipicephalus sanguineus (Latreille) adults (1070 males, 1441 females), 156 (5.5%) R. turanicus Pomerantsev adults (35 males, 121 females), 100 (3.6%) Rhipicephalus spp. nymphs and 45 (1.6%) Rhipicephalus spp. larvae. Dogs living outdoors, in rural areas and in close proximity to farm animals, were infested with higher numbers of ticks than dogs living indoors. Tick attachment sites were recorded on 237 dogs, harbouring a total of 1711 ticks. The most heavily infested sites were, in decreasing frequency, the ear pinnae, neck, interdigital skin folds, trunk, head, ventrum, extremities and the tail. Cutaneous lesions at the attachment sites were noticed in 129 dogs and then mainly in the more severely infested animals.     

Local immune response against larvae of Rhipicephalus (Boophilus) microplus in Bos taurus indicus and Bos taurus taurus cattle

Bos taurus indicus cattle are less susceptible to infestation with Rhipicephalus (Boophilus) microplus than Bos taurus taurus cattle but the immunological basis of this difference is not understood. We compared the dynamics of leukocyte infiltrations (T cell subsets, B cells, major histocompatibility complex (MHC) class II-expressing cells, granulocytes) in the skin near the mouthparts of larvae of R. microplus in B. t. indicus and B. t. taurus cattle. Previously naïve cattle were infested with 50,000 larvae (B. t. indicus) or 10,000 larvae (B. t. taurus) weekly for 6 weeks. One week after the last infestation all of the animals were infested with 20,000 larvae of R. microplus. Skin punch biopsies were taken from all animals on the day before the primary infestation and from sites of larval attachment on the day after the first, second, fourth and final infestations. Infiltrations with CD3⁺, CD4⁺, CD8⁺ and γδ T cells followed the same pattern in both breeds, showing relatively little change during the first four weekly infestations, followed by substantial increases at 7 weeks post-primary infestation. There was a tendency for more of all cell types except granulocytes to be observed in the skin of B. t. indicus cattle but the differences between the two breeds were consistently significant only for γδ T cells. Granulocyte infiltrations increased more rapidly from the day after infestation and were higher in B. t. taurus cattle than in B. t. indicus. Granulocytes and MHC class II-expressing cells infiltrated the areas closest to the mouthparts of larvae. A large volume of granulocyte antigens was seen in the gut of attached, feeding larvae.     

Rhipicephalus sanguineus: Observations on the parasitic stage on dogs in the Negev Desert of Israel

Sixteen dogs were studied for infestation with R. sanguineus in Kibbutz Ze'elim in the north-western part of the Negev Desert over a period of one year. The mean number of ticks per dog per month was 16.4. The majority of the ticks were adults: males (48.6%) and females (34.4%). The cars and abdomen of the dog were the predilection sites for the ticks. Male ticks were more abundant on the ears, whereas female ticks were more abundant on the ears and the abdomen. A strong correlation between tick numbers and the ambient temperatures was found. The mean percentage of dogs infested in the winter months was 16.6% and increased in the summer months to 34.4%. During winter, ticks were found more often on the ears and head of their hosts whereas in summer they were distributed mainly on the ears, headd and abdomen. The male: female ratio was higher in winter (2.3:1) than in summer (1.1:1).     

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.     

Amblyomma variegatum and associated diseases in the Caribbean: strategies for control and eradication in Guadeloupe

Amblyomma variegatum, introduced into Guadelopue 150 years ago, has recently spread in the Lesser Antilles and threatens North America. Two important diseases are associated with the tick: heartwater and dermatophilosis. Heartwater occurs in Guadeloupe, Marie-Galante and Antigua; acute dermatophilosis exists almost everywhere the tick is present. Both are very pathogenic for upgraded or newly-infested cattle. After 15 years of A. variegatum control in Guadeloupe, a balance is established between a tick population maintained at a low level by spraying acaricides and an animal population either completely resistant to heartwater and dermatophilosis (creole cattle) or regularly treated against ticks (upgraded cattle). An eradication campaign against A. variegatum in Guadeloupe, to avoid the spread of the associated diseases, appears technically difficult but possible, economically profitable, but socially completely utopian. We suggest for Guadeloupe a reinforced control of the tick with a persistent acaricide, hoping that a general decrease of the tick infestation rate on cattle will eliminate heartwater and acute dermatophilosis.     

Seasonal incidence and ecology of the tick Ixodes ricinus (Acari: Ixodidae) on grazing pastures in Western France

A longitudinal survey was carried out during a 2 year period in Western France to assess the infestation level of grazing pastures byIxodes ricinus ticks. Four farms were visited once a month and each of the grazing pastures was sampled in the centre and at the border using the blanket dragging method. A total of 3562I. ricinus (34 adults, 900 nymphs and 2628 larvae) were collected and the infestation was significantly higher during the first year (p<0.0001). The infestation level byI. ricinus varied between grazing pastures and farms. Grazing pastures in the vicinity of forest were more infested than the others, all through the study. The seasonal distribution of ticks showed peaks, with low fluctuations between farms, years and stages. Tick abundance could not be related to vegetation, but only to the vicinity of woods.     

C3 levels in the sera of rabbits infested and reinfested withIxodes ricinus L. and in midguts of fed ticks

Serum C3 levels of rabbits infested 3 times withIxodes ricinus L. females and C3 in midgut extracts of fed ticks have been measured by a single radial immunodiffusion test.From the first tick attachment, the mean serum C3 level of hosts increased. A peak of C3 occurred 6 days after the beginning of each infestation and was highest during the third infestation (about 8 times more pronounced than the level measured before the first). After the end of all infestations of the rabbits, the serum C3 level decreased and approached normal levels.Modifications of serum C3 levels during reinfestations influenced C3 contents in the blood meal of fed ticks. Midguts of ticks fed during the third infestation contained more C3 than midguts of ticks of the same engorged weights fed during the first or second infestations.     

Sites of attachment and density assessment of female Ixodes ricinus (Acari: Ixodidae) on dairy cows

A sample of 110 lactating dairy cows was examined to describe the attachment sites of female Ixodes ricinus ticks and to assess whether counts on one or two body areas can predict infestation and its level. Seventy per cent of the cows were infested by I. ricinus and the average tick burden on the infested cows was 15, ranging from 1 to 136. Preferred attachment sites were the axilla, udder/groin, neck, dewlap and flank. Udder/groin and axilla carryied respectively 35.3% and 44.1% of the total tick burden. To predict infestation (yes/no), sensitivity of counts on axilla, on udder/groin and on both areas was respectively, 76.6%, 80.6% and 94.8%. Total burden prediction equations based on count on axilla and udder/groin are presented.     

Prevalence of Borrelia burgdorferi sensu lato in ticks collected from migratory birds in Switzerland

The prevalence of ticks infected by Borrelia burgdorferi sensu lato on birds during their migrations was studied in Switzerland. A total of 1,270 birds captured at two sites were examined for tick infestation. Ixodes ricinus was the dominant tick species. Prevalences of tick infestation were 6% and 18.2% for birds migrating northward and southward, respectively. Borrelia valaisiana was the species detected most frequently in ticks, followed by Borrelia garinii and Borrelia lusitaniae. Among birds infested by infected ticks, 23% (6/26) were infested by B. lusitaniae-infected larvae. Migratory birds appear to be reservoir hosts for B. lusitaniae.     

The role ofRhipicephalus appendiculatus andR. evertsi evertsi males in inducing resistance in laboratory animals: preliminary studies

Guinea-pigs infested with male ticks of the speciesRhipicephalus appendiculatus, and rabbits infested withR. evertsi evertsi, acquired immunity to conspecific female ticks. The hosts were first infested with male ticks and thereafter were challenged with males and females of the same species. The mean weight of the engorged females ofR. appendiculatus fed on guinea pigs previously infested with male ticks was 509.0 (±41.4) mg compared with that of females fed on control guinea pigs (651.2±31.8 mg). Similar weight differences were observed forR.e. evertsi females which fed on rabbits previously infested three times with male ticks. The mean weight of the female ticks which fed on these rabbits was 520.1 (±29.8) mg compared with 640.7 (±30.2) mg ofR.e. evertsi females which fed on control hosts. The concentration of gammaglobulins in the sera of rabbits was monitored at various intervals after the first infestation. It was found, for the first time, that infestation of laboratory animals with male ticks conferred immunity, but to a lesser degree than infestation with both sexes. It was also shown that the level of gammaglobulins increased from 3.4±0.28 g l^–1 to 7.3±0.24 g l^–1 in sera of rabbits hosts as a result of the feeding activity of males, but to a lesser extent than in sera of rabbits on which both sexes had fed (10.8±2.4 g l^–1).     

Immune responses to Dermatophilus congolensis infections.

Complex mechanisms underly the establishment of dermatophilosis, an exudative and proliferative skin disease of ruminants. This multicomponent system involves the bacterium Dermatophilus congolensis, transmission by various routes including flies, host genetic factors and immunosuppression by Amblyomma variegatum ticks. Here, Nick Ambrose and colleagues summarize recent evidence for an association between A. variegatum and severe chronic dermatophilosis in cattle. Breed-based differences in resistance to dermatophilosis are probably related to immunity to ticks or resistance to the immunosuppressive effects of ticks. Immunity to dermatophilosis might involve non-classic responses mediated by CD1 antigen presentation and gammadelta T cells. Progress towards vaccination is further complicated by strain-specific acquired immunity to D. congolensis.     

Female tick Hyalomma marginatum marginatum salivary glands: preliminary study on protein changes during feeding process and antigens recognized by repeatedly infested cattle

Proteins extracted from salivary glands of unfed, three days and five days fed adult Hyalomma marginatum marginatum were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). We have noticed changes during the three feeding steps. Some proteins disappeared during feeding process (23, 38, 39, 40 to 50, 95 and 112 kDa), they might be proteins which were converted in other substances and are secreted. Other antigens (13 to 14, 20, 25, 29, 165 and 210 kDa) were synthesized as a result of tick attachment and feeding. They may be related to growth and development or are the ciment which fixed the adult. Also, three Holstein calves were infested five times with 100 pairs of adult ticks of the same species. The five infestations were performed two weeks from the previous infestation. The sera before infestations and after each infestation were used in western-blot analyses to identify antigens from five days salivary gland extracts of the primary infestation of ticks. Three antigens (18.7, 50 and 80 kDa) were revealed weakly after the first and the second infestations by sera samples but not at infestation onward. Others (13.5, 17 to 18.5, 25, 30, 70, 133, 176 and 193 kDa) were revealed only by sera taken after manifestation of resistance (third infestation). A 13.5 kDa antigen was particularly revealed when resistance had appeared and became more evident after the fourth and fifth infestations. The late antigens recognized might be associated with establishment of calves resistance against ticks.     

Study of the sustained speed of kill of the combination of fipronil/amitraz/(S)-methoprene and the combination of imidacloprid/permethrin against Dermacentor reticulatus, the European dog tick

The sustained speed of kill against Dermacentor reticulatus of two topical combinations, one containing fipronil/amitraz/(S)-methoprene and the other, imidacloprid/permethrin, was evaluated in dogs. Two treated groups and one untreated control group of eight adult Beagle dogs each were randomly formed based on pre-infestation rates and bodyweight. Each treatment was administered topically once on Day 0, according to the recommended label dose and instructions for use. All dogs were infested with 50 adult unfed D. reticulatus starting on Day 1, then weekly, for a total of five weeks. While most studies determine tick efficacy at 48 hours (h), in this study, all remaining ticks were counted and categorized 24 h following each infestation. The numbers of ticks (living or dead) that remained attached on treated dogs were compared to those on the control animals. The percent reduction of attached ticks (disruption of attachment) at 24 h on dogs treated with fipronil/amitraz/(S)-methoprene remained above 92% for four weeks. The reduction of attached ticks at 24 h on dogs treated with imidacloprid/permethrin did not reach 80% during the entire study. The number of ticks attached at 24 h was significantly (p<0.05) lower in the fipronil/amitraz/(S)-methoprene group than in the imidacloprid/permethrin group in assessments on Days 2, 15, 22, 29 and 36. When assessing efficacy based upon live ticks on treated versus control dogs, fipronil/amitraz/(S)-methoprene 24 h efficacy was above 95% for four weeks, decreasing to 77.8% at Day 36. The 24 h efficacy of imidacloprid/permethrin ranged from 56.2% to 86.7% through Day 29, never achieving 90% throughout the study. The 24-hour efficacy of fipronil/amitraz/(S)-methoprene was significantly (p<0.05) higher than imidacloprid/permethrin at all time points, including Day 36.     

Ticks Ixodes uriae and the breeding performance of a colonial seabird, king penguin Aptenodytes patagonicus

High densities of penguins in their colonies and the continuous use of these sites over consecutive reproductive periods increase the risk of development of tick populations. We have studied the effects of tick parasitism by Ixodes uriae in a colony of king penguins Aptenodytes patagonicus at Possession Island during three breeding seasons. We investigated the prevalence and periods of tick infestation during the one-year breeding cycle of penguins. The effects of tick parasitism on penguin breeding performance were assessed from photographs of the colony and with an automatic penguin identification system. We compared two groups of penguins carrying individual subcutaneous electronic tags, one group breeding in an infested area and the other in a non-infested area. Tick feeding activity was coincident with the periods when adult penguins stayed ashore for six days or more, i.e. during the incubating period. This duration corresponds to the duration of a tick meal on the host. The level of infestation varied between years. Penguins showed a lower incubating success in infested areas during a year of high infestation. In an infested area, individuals seen with ticks had a lower breeding success in rearing a one-year old chick than those seen without ticks.