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     

Tick infestations of birds in coastal Georgia and Alabama

Mist-netted birds were examined for ticks on Jekyll Island, Glynn Co., Georgia (32 bird species) in 1996-1998, and at Fort Morgan, Baldwin Co., Alabama (36 species) in 1998 during fall migration. Sixty-two (14.7%) of 423 birds from Jekyll Island and 22 (13.3%) of 165 birds from Fort Morgan were infested with ticks. The mean number of ticks per infested bird was 2.0 on Jekyll Island and 6.3 at Fort Morgan. Ten species of birds were infested with ticks on Jekyl1 Island where 87% of all ticks were recovered from 3 species: the common yellowthroat (Geothlypis trichas), gray catbird (Dumetella carolinensis), and northern waterthrush (Seiurus noveboracensis). Eight species of birds were infested with ticks at Fort Morgan where 83% of all ticks were recovered from 3 species: the brown thrasher (Toxostoma rufum), swamp sparrow (Melospiza georgiana), and common yellowthroat. Six species of ticks (Amblyomma americanum, Amblyomma maculatum, Haemaphysalis leporispalustris, Ixodes brunneus, Ixodes minor, and Ixodes scapularis) were recovered from the Georgia birds, whereas 3 species (A. maculatum, H. leporispalustris, and Ixodes dentatus) were recovered from the Alabama birds. Attempts to isolate Borrelia burgdorferi sensu stricto, the etiologic agent of Lyme borreliosis, from Ixodes spp. ticks recovered from birds were unsuccessful.     

Tick (Dermacentor albipictus)-induced winter hair-loss in captive moose (Alces alces)

Five captive moose calves each infested with 42,000 larval Dermacentor albipictus, six calves each infested with 19,000-21,000, and five control moose were observed for changes in hair-loss, body condition and number, stages, and distribution of the tick. Winter hair-loss was observed only in moose infested with ticks and was correlated positively with the total number of adult ticks. Hair-loss associated with ticks was minimal from October to January, but rapidly increased from February to April when up to 44% of hair had been removed. The pattern of hair-loss was similar in all moose with the neck, shoulders, withers, and perianal areas losing the most hair. Moose with extensive premature hair-loss had less pericardial and abdominal visceral fat than moose with little or no hair-loss.     

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).     

Incompetence of catbirds as reservoirs for the Lyme disease spirochete (Borrelia burgdorferi)

We compared the relative infectivity to vector ticks of gray catbirds (Dumetella carolinensis) and white-footed mice (Peromyscus leucopus) for the Lyme disease spirochete (Borrelia burgdorferi). Of 28 catbirds captured in a site enzootic for this agent, 18 were infested by immature Ixodes dammini, the tick vector. By comparison, each of 32 mice sampled concurrently from the same site was infested, and by about 10 times as many ticks as were found infesting the 3 most commonly netted bird species. Although 76% of noninfected larval ticks placed on these mice in a xenodiagnosis became infected, none of the ticks similarly placed on 12 catbirds did so. Spirochetes were detected in ticks derived from 2 Carolina wrens (Thryothorus ludovicianus) and a common yellowthroat (Geothlypis trichas), but these species' potential contribution to infecting ticks does not compare with that of mice. Thus, although birds may help establish new foci of ticks, catbirds, at least, do not appear to contribute as reservoirs of infection.     

The effect of feeding immature Karoo paralysis ticksIxodes rubicundus (Acari: Ixodidae) on the metabolic rate of the rock elephant shrew

The effect of feeding immature Karoo paralysis ticks (Ixodes rubicundus) on the resting metabolic rate (RMR) of their principal natural host, the rock elephant shrew (Elephantulus myurus), was investigated under laboratory conditions. The elephant shrews were artificially infested with numbers of ticks simulating natural burdens. The RMR of the elephant shrews was quantified by measuring the oxygen consumption in an open through-flow system. The RMR of hosts infested only with larvae did not differ from that of the control group. Those infested with nymphs, or nymphs and larvae, had significantly lower RMR's compared to the control animals. There were no signs of paralysis in any of the infested hosts.     

The degree of infestation of ixodid ticks,collected from humans,with the tick-borne encephalitis virus in the territory of tomsk and its environs

Tick-borne encephalitis (TBE) virus was determined in ticks I. persulcatus and I. pavlovskyi, collected from humans attacked by ticks in city parks, forest-parks in city outskirts, and in suburban forests, by the enzymelinked immunosorbent assay method (ELISA). It was found that, in spite of I. pavlovskyi being the dominating species in Tomsk and its suburbs, the majority of ticks that attacked humans belonged to I. persulcatus. In ticks that possessed no sighs of the beginning of engorgement (hungry ticks), infestation with TBE virus was revealed by ELISA method less frequently. Percentage of I. persulcatus and I. pavlovskyi, infested with TBE virus, constituted 9.43 % and 3.7 %, respectively. In partly engorged ticks, it constituted 48.78 % and 35.0 %, respectively. In suburban forests, humans were also attacked by I. persulcatus more frequently. In this species, the fraction of infested specimens constituted 12.73 % and 41.54 % in partly engorged and hungry ticks, respectively. In I. pavlovskyi, this percentage constituted 6.06 % and 25 %, respectively. In other words, in all the groups examined, the fraction of infested ticks was noticeably lower in I. pavlovskyi; at the same time, the TBE virus is significantly more frequently revealed in partly engorged ticks.     

Resistance to Boophilus microplus (Canestrini) in genetically different types of calves in early life.

Tick resistance and blood composition were studied in British (1/2 Shorthorn x 1/2 Hereford) and zebu (1/2 Brahman x 1/2 British) calves from birth to 33 days of age in a tropical grazing area in which B. microplus is endemic. Calves of the 2 breeds were either naturally infested or were, in addition, artificially infested with 5,000 larvae at 2 and 9 days of age. Total numbers of mature female ticks carried from either type of infestation were significantly lower (P less than 0.01) on zebu than on British calves. In the artificially infested calves of both breeds, the total number of ticks maturing between 20 to 26 days of age was significantly higher (P less than 0.01) than the number maturing between 27 to 33 days of age emphasizing that a major component of resistance is acquired. However, in the naturally infested calves, breed differences in the numbers of ticks maturing during these 2 periods suggested the presence of genetic differences in innate resistance. Within breeds, total tick numbers carried during the study were negatively correlated with calf weight gain and with the concentrations of serum albumin, total protein, and cholesterol.     

Increased mortality of black-browed albatross chicks at a colony heavily-infested with the tick Ixodes uriae

At Bird Island, South Georgia, we studied the effects of the tick Ixodes uriae on survival of chicks at two colonies of the black-browed albatross Diomedea melanophrys, one where most chicks were infested with ticks, the other where most chicks were tick-free. When the two colonies were compared, it was found that the colony heavily-infested with ticks had significantly greater chick mortality than the colony lightly-infested with ticks. However, within each of the two colonies, there was no significant difference in survival between chicks with ticks and those without ticks.     

Body mass of wild ring-tailed lemurs in Berenty Reserve,Madagascar, with reference to tick infestation: a preliminary analysis

In 1999, we measured the body mass of 101 wild ring-tailed lemurs (Lemur catta) inhabiting the Berenty Reserve, Madagascar. In addition, we counted the number of ticks [Haemaphysalis (Rhipistoma) lemuris Hoogstraal, 1953] infesting their facial skin and external auditory meatuses. For both males and females, the body mass appeared to increase until the age of 3 years. With the apparent exception of infants, there were no sexual differences in body mass. Within a group, higher-ranked adult males tended to be heavier than lower-ranked males. In contrast, there was no consistent correlation between the body mass of females and their ranks. Among the study groups, there was a small difference in body mass and significant difference in the number of ticks infesting the facial skin and external auditory meatuses. In particular, lemurs of a group who inhabited an area of gallery forest in the study area exhibited the smallest values of body mass and were severely infested with ticks. Such group variations were not consistently correlated with the reproductive parameters of the study groups. In three groups moderately infested with ticks, ticks infested adult males and subadults more heavily than adult females, juveniles, and infants.     

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.     

Tick infestations of white-tailed deer in Alabama.

Four species of ticks were collected from 537 white-tailed deer (Odocoileus virginianus), examined during the hunting seasons (November to January) of 1988-89 and 1989-90 at selected locations in Alabama (USA). Ixodes scapularis was the most common tick recovered (2,060 specimens) and infested 54% of the deer. Dermacentor albipictus was the second most frequent tick (1,253 specimens) and infested 15% of the deer. Amblyomma americanum was the third most frequent tick (315 specimens) and infested 24% of the deer; this was the only species of tick collected from deer at all sampling locations. Amblyomma maculatum was an infrequent parasite (five specimens) and infested only 1% of the deer; this tick species was only recorded during the 1989-90 season. Year-to-year and geographical differences in tick infestation parameters were noted. The data are compared with those reported for previous surveys of ticks infesting white-tailed deer in Alabama and adjacent states.     

Bird ticks in an area of the Cerrado of Minas Gerais State, southeast Brazil

In the present study the tick prevalence, mean intensity of infestation and species were recorded on birds captured between January 2009 and December 2010 in the Ecological Station Pirapitinga-ESEC from Minas Gerais State, Brazil. A total of 967 birds, from 15 families and 40 species were captured and 165 (17.1 %) individuals were parasitized by ticks. Of these 160 (97 %) belonged to the order Passeriformes. Five tick species were identified: Amblyomma longirostre (n = 274) was the most common species followed by Amblyomma parvum (n = 43), Amblyomma nodosum (n = 39), Amblyomma ovale (n = 24) and Riphicephalus sanguineus (n = 7). None of 61 unengorged larvae molted to nymph. The mean intensity of infestation was 2.7 ± 2.4 ticks per bird (448 ticks/165 birds) ranging from 1 to 10. Only 19 (11.4 %) birds were infested with one species of tick. The remaining birds were infested by two, three or four species of ticks. Also new hosts for all five ticks were recorded. Only nymphs were recorded throughout the year with two similar peaks during autumn and winter 2009 and 2010.     

Risk for the introduction of exotic ticks and pathogens into Italy through the illegal importation of tortoises,Testudo graeca

In April 2008, 585 tortoises illegally imported into Italy from North Africa were examined for the presence of ticks. Of these, 221 tortoises (37.8%) were infested with a mean intensity of 3.9 ± 3.1 ticks (range 1–17 ticks). A total of 798 ticks (672 males, 125 females and one nymph) were collected and identified as Hyalomma aegyptium (L.) (Acari: Ixodidae). The overall male : female ratio observed was 5 : 1. The prevalence and mean intensity [±standard deviation (SD)] of ticks were higher among male (67.4%, 4.0 ± 3.2) than female (55.6%, 3.8 ± 3.1) tortoises, although this difference was not significant. By contrast, the prevalence and mean intensity of ticks were significantly higher on tortoises weighing >100 g (61.5%, 4.0 ± 3.2) compared with tortoises weighing <100 g (12.1%, 2.1 ± 1.1). Of the infested tortoises, 89.8% had ticks on their hind limbs, 21.0% on forelimbs, 18.6% on the tail and pre‐anal area, and 4.8% on the head; thus the hind limbs were evidently the preferred attachment site. The present report highlights the need to develop surveillance systems to prevent the introduction and spreading of exotic ticks and tick‐borne pathogens in Italy and other European countries.     

Evaluation of the one-side tick counting technique and of the level of infestation of bovines with Rhipicephalus microplus

Counting ticks on one side of a bovine has been widely used to estimate the overall number of ticks; however, the accuracy of this method has not been determined. This work aimed to evaluate the one-side technique for counting ticks, identify bovines with a higher level of infestation, and determine the prevalence of infestation of adults and calves. To evaluate the one-side technique, ticks were counted on both sides of 352 bovines from three farms in nine months, and total numbers were correlated with the numbers counted on the left sides. The intraclass correlation coefficients reached values >0.99 for all farms, independent of the season. These results demonstrated that counting ticks on one-side and multiplying by 2 is a reliable method for estimating the overall number of ticks. To evaluate the level of infestation of various bovines, ticks were counted monthly, for 12 months, on the same bovines from seven farms. An animal was considered highly infested if the Anscombe residuals from a negative binomial GLM were ≥4, at least 2×. The number of bovines with infestation levels higher than expected varied among farms from zero to 3. Using this method, it is possible to evaluate the most infested bovines in order to remove them from the herd. The prevalence of infestation in calves reached 100% in five of the seven farms and 3- to 15-month-old calves had significantly higher infestation than adults.

     

Invasion of West African cattle by the tick Amblyomma variegatum

Studies in Cameroon and Burkina Faso examined the invasion process of cattle by adult Amblyomma variegatum Fabricius (Acari: Ixodidae) ticks. Nearly all the ticks picked up in the pasture during grazing were found on the limb ends, near the hooves, where they temporarily attached. Then when the cattle lay down, the ticks moved from the feet towards the predilection sites, where they attached definitively. Many ticks disappeared during this displacement. All the female ticks and approximately 70% of the males were thus unable to attach to the predilection sites as long as the pioneer males had not attached and started to produce attraction-aggregation-attachment pheromones. Nevertheless, A. variegatum females and males attached to the feet in similar numbers during grazing, whether the cattle were already infested or not, indicating that stimuli originating from the hosts are powerful enough to attract both sexes. After attachment of the pioneer males, the number of ticks that successfully reached the predilection sites increased. However, even on infested animals, 40-50% of A. variegatum ticks found near the hooves after the grazing periods disappeared during the night following their capture. When moving from the temporary attachment sites towards the final ones, one-third of the ticks changed the individual host. Considering this two-stage infestation process, it is suggested that a targeted tick control, using a foot-bath, might greatly reduce cattle infestation. In particular, it could be effective in traditional herds, with animals grazing permanently during the day, lying down only once back in the night pen.     

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.     

Experimental evaluation of birds as disseminators of the cosmopolitan tick Rhipicephalus sanguineus (Acari: Ixodidae)

Rhipicephalus sanguineus is believed to be the most widespread tick species of the world and its dissemination seems to rely on the diffusion of its main host, the dog. Empirical observations indicate that several bird species in urban areas regularly steal dog food. Such circumstances create a chance for R. sanguineus ticks to climb on birds and carry ticks to another site. In this work we evaluated experimentally the likelihood of birds (chicks) to either feed and/or carry R. sanguineus ticks from an infested site to another and to infest a host (rabbit) in the new location. Chicks were not suitable hosts for R. sanguineus ticks. Not a single adult tick engorged on chicks, yield as well as weight of engorged larvae and nymphs were very low and feeding period of these ticks was very long. However, a few larvae and, chiefly, nymphs were delivered to a new location either mechanically or after attachment and engorging total or partially on chicks. A few of these ticks fed successfully on rabbits. Further evidence on the capacity of birds to introduce R. sanguineus into non-infested dog settings should be provided by systematic examination of birds from urban areas, close to tick infested households.     

The incidence of the tick parasite Ixodes uriae in Kittiwake Rissa tridactyla colonies in relation to the age of the colony, and a mechanism of infecting new colonies

Kittiwakes Rissa tridactyla (683 chicks and 64 adults) were examined for ectoparasites in three breeding areas: Isle of May (Firth of Forth, Scotland; eight colonies of approximately known age of occupation on natural sites), North Shields and Gateshead (Tyne and Wear, England; well established colonies of known age on buildings). All the 208 ticks collected were Ixodes uriae. On the Isle of May, a colony which had only been established for 7 years was already infested by ticks. Tick incidence increased significantly with the length of colonization of the area during the first 30 years. Age of colonization did not have an effect after 30 years. In Gateshead only a single adult among the 127 birds examined had a tick. No ticks were found on the 106 chicks born at North Shields checked in 1987 or in 1988. However, among nine visiting newly-fledged chicks from neighbouring colonies caught at the North Shields colony, six had either ticks or scars of previous infestation. Some visiting chicks remained for several days in the host colony and were even fed by the owners of visited nests. Ixodes uriae may thus spread from one colony to another during visits of newly-fledged infested chicks to neighbouring colonies. The absence of any infestation in old colonies (38 years in North Shields and 17 years in Gateshead) on buildings that are regularly visited by newly fledged infested chicks, suggests that buildings may lack the rock refuges necessary for tick survival from one year to the next. In this respect Kittiwake colonies on buildings are rather atypical.