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Digenetic trematodes are important parasites of humans and animals. They have complex life cycles and typically infect a gastropod as the first intermediate host.

Before the work of Hoogstraal and colleagues in the 1960s and 1970s, there was considerable confusion as to the taxonomic definition, distribution, ecology and biology of A. persicus due to confusion with a variety of other species. Records prior to 1970, particularly those from outside of the currently known range of this species, should therefore be treated sceptically.

Emel’yanova (1979), quoting Cerný (Folia Parasitologica 16:32, 1969), suggests that Ixodes crenulatus is in fact a species group, based on morphological and ecological properties.

Haemaphysalis punctata is a three-host tick with a natural life cycle of 1–3 years (Nosek et al. in Bulletin of the World Health Organization, 36:49–59, 1967; Nosek in Zeitschrift fur Parasitenk, 37:198–210, 1971; Liebisch et al. in Berliner und Munchener Tierarztliche Wochenschrift, 89:477–480, 1976; Farkas et al. in Ticks and tick-borne diseases: geographical distribution and control strategies in the Euro-Asian region, CABI, Boston, pp 6–26, 2012).

Rhipicephalus guilhoni is a three-host tick; the life cycle of which takes a year to complete. It has been recorded from a variety of hosts including domestic animals, mostly cattle and sheep, but also dogs and cats, and wild animals including carnivores, insectivores, artiodactyls, perissodactyls, lagomorphs, rodents and non-passerine birds. This species has also been recorded from humans.

The genus Dermacentor is a representative of the Nearctic, Palaearctic, Asian and Afrotropical tick fauna. Around 14 species of the genus are found in the Palaearctic region, but only two are present in the Western Palaearctic. General works on the genus include Filippova and Panova (1986, 1989) and Filippova et al. (1985).

Ixodes unicavatus is a rare species which is usually found in coastal areas where it is parasitic predominantly on colonial seabirds or birds that frequent the coast, particularly cormorants Phalacrocorax aristotelis and P. carbo.

Haemaphysalis Koch, 1844, is a widely distributed genus of ticks with 167 accepted species recognized worldwide (Guglielmone et al. in The hard ticks of the world (Acari: Ixodida: Ixodidae). Springer, Heidelberg, p 738, 2014). The larvae, nymphs and at least one adult stage are described for only 98 (59%) of all the known species. Nevertheless, most parasitic stages of species within the Palaearctic are known (Guglielmone et al. in The hard ticks of the world (Acari: Ixodida: Ixodidae). Springer, Heidelberg, p 738, 2014).

Ixodes persulcatus, the taiga tick, is a three-host tick. Under laboratory conditions (20 °C, 12 h light/dark cycle) the life-cycle takes about 250 days (Konnai et al. in Jpn J Vet Res 55:85–92, 2008). It is a generalist tick, feeding on a variety of different animal species, ranging from reptiles to birds to mammals. The immature developmental stages prefer to feed on small and medium-sized mammals and birds, while the females parasitize large mammals, such as deer, cattle, sheep or hares (Gray in Exp Appl Acarol 22:249–258, 1998).

There is some confusion concerning records of Ixodes ventalloi and Ixodes festai (Petney et al. in Appl Parasitol 37:96–98, 1996; Guglielmone et al. in The hard ticks of the world. Springer, Heidelberg, 2014). Because of this diagnostic uncertainty, no references published before Gilot and Perez (1978) will be used here.

Hyalomma aegyptium is a three-host tick (Siroký et al. in Exp Appl Acarol 40:279–90, 2006). Under laboratory conditions, the life cycle is completed within 147 days (Siroký et al. in Exp Appl Acarol 54:277–84, 2011). Although tortoises (Testudinidae, mainly genus Testudo) are the dominant hosts for all of the developmental stages, a wide variety of other hosts are known, including cattle, deer, wild pigs, horses, camels, dogs, hedgehogs, hares, rodents, birds and lizards (Hoogstraal and Kaiser in Ann Entomol Soc Am 53:457–458, 1960; Apanaskevich in Parazitologiia 37:47–59, 2003).

The life cycle of Ixodes trianguliceps may last from 2 to 5 years, depending on the climatic conditions (Balashov in Entomol Rev 76:625–637, 1997).

The genus Hyalomma contains species of ticks involved in the transmission of a number of significant pathogens in the Mediterranean region, Africa and Asia. All species in the genus are restricted to the Palaearctic, Indo-Malaysian and Afrotropical regions. The immatures of these species pose considerable difficulties in identification and we strongly advise researchers not to attempt to identify the engorged nymphs or larvae of Hyalomma to species level. It is of extreme importance to keep the engorged nymphs alive and allow them to moult to obtain adults.

In general, very little is known about the biology of this tick. Information about the three-host life-cycle comes mainly from laboratory studies.

Ixodes frontalis is an exophilic, three-host tick with a life-cycle of 1 year in its natural environment.

Haemaphysalis concinna is a three-host tick the life cycle of which can be completed within 3 years under natural conditions (Nosek in Z Parasitenkd 36:233–241, 1971).

There are a total of 59 species of ticks in this genus, grouped into about 9 subgenera, that have been reported from the Palaearctic region (Guglielmone et al. 2014).

Hyalomma impeltatum can exhibit either a three-host or a two-host life cycle (Apanaskevich and Horak in Systematic Parasitology 73:199–218, 2009).

There is currently a discussion as to whether the eastern Palaearctic tick Ixodes redikoverzi Olenev, 1927 is a synonym of Ixodes acuminatus.

The life cycle of A. reflexus comprises eggs, larvae, two to four nymphal stages and the adults. Laboratory studies showed that the number of nymphal instars seems to depend on the outside temperature, with cooler temperatures leading to fewer instars. The life cycle might be as long as 3–11 years in Central Europe. Hosts are predominantly domestic pigeons (Columba livia domestica). Other hosts include rock pigeons (C. livia), turtle doves (Streptopelia turtur), swifts, swallows, owls, crows, several passerine birds and chickens.

This is considered to be a polytypic species containing a number of morphologically definable subspecies: Haemaphysalis erinacei erinacei Pavesi, 1844, Haemaphysalis erinacei taurica Pospelova-Schtom 1940 and Hae. e. turanica Pospelova-Schtom 1940.

To date, almost 900 species of ticks have been described. The three existing families consist of the Argasidae (soft ticks; ca. 191 species), the Ixodidae (hard ticks; ca. 702 species) and the Nuttalliellidae with only one species (Nuttalliella namaqua). They transmit more pathogen species to humans, livestock, companion animals and wildlife than any other blood-sucking arthropod species. However, research focuses predominantly on the most abundant tick species, such as Ixodes ricinus in Europe, Ixodes scapularis in the USA or Rhipicephalus sanguineus s.l. worldwide, and their role in the transmission of diseases. For most other less abundant tick species, information on the biology, ecology and vector capability is rare, as described in the present book. However, tick species that are not a direct threat to humans or animals can still be important for the maintenance of enzootic cycles for different pathogens. Therefore, to understand the eco-epidemiology of various diseases, it is essential to study the interactions between ticks, their hosts, the pathogens and their biotic and abiotic environment. In order to achieve such an understanding, collecting ticks is necessary. The type of collection, as well as the quality of results, depends on the host-seeking behaviour, the life history stages and the natural habitat of the ticks.

To date, there are eight species of the genus Rhipicephalus known from the Western Palaearctic, namely, R. guilhoni Morel and Vassiliades, 1963 (so far only from the Canary Islands, probably introduced); R. camicasi Morel, Mouchet, and Rodhain, 1976 (so far only in Egypt); R. sanguineus s.l.; R. turanicus Pomerantzev, 1940; R. pusillus Gil Collado, 1936; R. rossicus Yakima and Kohl-Yakimova, 1911; and R. bursa Canestrini and Fanzago, 1878. The eighth species is R. annulatus Say, 1821, which was formerly included in the genus Boophilus.

Argas polonicus is a parasite of rock pigeons (Columba livia). It was first found in Krakow, Poland, where trumpeters of St. Mary’s Church were frequently bitten by this tick when their hosts were driven from their resting places. Molecular and biochemical tests based on cuticular hydrocarbon composition supported the early morphological observations reporting this tick as a new species.

Only limited information is available on this species. Other than some records used in its original description, only a few data on its distribution are available. It is an argasid which has some peculiar morphological features, as described by Hoogstraal (1957). The larva has peritremes, a kind of elongated structure on the lateral and ventral sides of the idiosome, which are related to air exchange. These are most similar to those found in predatory and free-living mesostigmatid mites. This unusual feature, plus others found in the adult stage, provided enough background to create the subgenus Secretargas.

It has been suggested that Ixodes uriae is a complex of species, although definitive taxonomic data are lacking.

The tree-hole tick, Ixodes arboricola, is a nest-dwelling species commonly hosted by hole breeding passerines. It occurs exclusively in tree holes and is thus adapted to this environment, including prolonged attachment and detachment at night to ensure that it remains only in tree-holes.

Hoogstraal (1958) and Filippova (1966) provide detailed descriptions of the morphology of the different stages of A. vespertilionis.

Hyalomma dromedarii has been recorded as a one-, two- or three-host species, although the two-host life cycle is thought to be the most common with attached larvae detaching as engorged nymphs.

Striped mice, Rhabdomys pumilio, were trapped over a period of 17 months in the Thomas Baines Nature Reserve, and placed in cages, over water, until all the ticks they harboured had detached. The mice were then returned to the reserve. Four ixodid tick species were recovered from the mice of which the larvae and nymphs of Rhipicephalus follis and Rhipicephalus simus were the most numerous. Most larvae of R. follis detached from mice trapped from March to July, and most nymphs in March and from June to September. Most larvae of R. simus detached from mice trapped from December to March, and most nymphs from January to March and during May and June. Seven ixodid tick species were collected from striped mice, house rats, Rattus rattus, vlei rats, Otomys spp. and Praomys sp. captured in the vicinity of human dwellings or animal holding facilities in the Grahamstown district. The striped mice captured in the Thomas Baines Reserve harboured considerably larger numbers of ticks than any of the rodent species in the more urbanized localit

The risk of Borrelia burgdorferi infection and the value of antibiotic prophylaxis after tick bite are controversial. In this study, performed in two areas of southwestern Germany, ticks were collected from 730 patients and examined by the polymerase chain reaction (PCR) for B. burgdorferi. To assess whether transmission of B. burgdorferi occurred, the patients were clinically and serologically examined after tick removal and during follow-up examinations. Data from all tick bites gave a total transmission rate of 2·6% (19 patients). Eighty-four ticks (11·3%) were PCR positive. Transmission occurred to 16 (26·7%) of 60 patients who were initially seronegative and could be followed up after the bite of an infected tick. These results indicate that the transmission rate from infected ticks in Europe is higher than previously assumed. Examination of ticks and antibiotic prophylaxis in the case of positivity appears to be indicated.

A total of 7,334 crop and/or stomach contents from 239 species of South African birds were examined for ticks. Only 36 ticks were found: 24 in 21 cattle egret (Bubulcus ibis), four in four helmeted guineafowl (Numida meleagris), one in a crowned plover (Vanellus coronatus) and seven in a single lilacbreasted roller (Coracias caudata). In most cases identification of the ticks was not possible although the genera Boophilus, Hyalomma and Rhipicephalus were represented. With the exception of the oxpeckers which were not represented in this survey, we conclude that predation by birds on ticks is uncommon in South Africa.

2004 The status of Argas persicus in Australia has been a matter of controversy for over 25 years. Although early records of A. persicus sensu stricto are common, a major revision of the genus indicated that these records refer to A. robertsi, first described in 1968 from northern Australia, and to an ldquoundescribedrdquo member of the complex occurring in the south. Here, we show that A. persicus sensu stricto does occur in southern Australia and is the only species of Argas in the area recorded from poultry. Another undescribed species belonging to the A. persicus complex, from crowsrsquo nests near Lake Eyre in South Australia, was also discovered. This information is of considerable epidemiological significance, as A. persicus sensu stricto is a major vector for a number of highly pathogenic diseases of poultry, not all of which have yet been recorded from Australia.

Arthropod and helminth parasites are classified together as macroparasites on the basis of ecological similarities (Anderson and May 1979). The relationship between each group and its host species for such parameters as ratio of body size, intrinsic population growth rate, life span and the pathological significance of their interaction are comparable but significantly different from microparasites (viruses, bacteria, protozoans) and parasitoids.

A total of 1,640 stomach contents from 56 South African species of small and medium sized mammals were examined for ticks. Only six ticks were found in three specimens of the caracal Felis caracal. Although identification of the tick species was not possible owing to fragmentation and partial digestion, the genus Haemaphysalis was represented in four of these cases. We conclude that predation by small and medium sized mammals on ticks is uncommon in South Africa.

Data collected on both free-living and parasitic tick populations are likely to be overdispersed. The use of means from few replicate samples of overdispersed data as quantitative estimators of tick population density is in turn likely to lead to inaccurate interpretations which may be scientifically misleading. In this paper ways of estimating overdispersion are listed and suggestions for the use of correct statistical tests for handling overdispersed data are given.

The parapatric boundary between the reptile ticks. Aponomma hydrosauri and Amblyomma limbatum, near Mt Mary, South Australia, coincides with a vegetational ecotone. Samples of litter from each side of the tick boundary showed considerable heterogeneity, but there were consistent differences in the composition and quantity of litter. North of the boundary, where Amb. limbatum is found, there is less litter and an absence of Eucalyptus leaves in the litter. Since the litter retards evaporative water loss, and Ap. hydrosauri is less tolerant of dehydration, reduced litter quantity may reduce the fitness of colonizing Ap. hydrosauri. In laboratory and field trials, larvae and nymphs of both tick species chose litter microhabitats in preference to bare soil, with the exception of fed Ap. hydrosauri larvae which, in trials with litter from north of the boundary, rarely moved from the bare soil. This behaviour may also reduce the fitness of colonizing Ap. hydrosauri. The two species adopted different positions in the litter. Ap. hydrosauri were predominantly found on the surface, at the interface between soil and litter as fed larvae, and on or under the surface as nymphs. Amb. limbatum larvae were more often buried under the surface, while nymphs were found mostly in the litter above the soil surface. Hypotheses to explain the maintenance of the parapatric boundary are discussed in the light of these results.

A comparative, quantitative study is made of the overlap in host range of and relative infestation levels of the bont tick, Amblyomma hebraeum and the South African tortoise tick, Amblyomma marmoreum. Although there is very little overlap in the adult host ranges, immatures occur on a similar range of species. Niche overlap of between 30% and 90% is common for both wild and domestic hosts. This overlap suggests that A. marmoreum may be of more significance in the epidemiology of the disease heartwater than has previously been considered. Zusammenfassung Vergleichende Untersuchungen zum Wirtsspektrum von Amblyomma hebraeum und Amblyomma marmoreum (Acari, Ixodidae), zwei sudafrikanische Vektoren der Herzwassersucht Es wurde eine vergleichende, quantitative Untersuchung uber die Kongruenz des Wirtsspektrums und den Grad des Wirtsbefalls bei der “bont” Zecke Amblyomma hebraeum und der sudafrikanischen Schildkrotenzecke Amblyomma marmoreum erstellt. Obwohl es bei ausgewachsenen Zecken nur eine geringe Kongruenz des Wirtsbefalls gibt, treten Larven und Nymphen bei einem ahnlichen Spektrum von Arten auf. Eine Nischenkongruenz von 30% bis 90% ist sowohl bei Wirten unter Wildtieren als auch unter Haustieren verbreitet. Diese Kongruenz last vermuten, das Amblyomma marmoreum eine grosere Bedeutung bei der Epidemiologie der Herzwassersucht haben konnte, als man bisher angenommen hat.

The hosts, sites of attachment, life cycle, habitat requirements and seasonal abundance of Amblyomma astrion, Amblyomma cohaerens, Amblyomma gemma, Amblyomma hebraeum, Amblyomma lepidum, Amblyomma marmoreum, Amblyomma pomposum, Amblyomma sparsum, Amblyomma tholloni and Amblyomma variegatum, the 10 potential vectors of heartwater in Africa, are listed. Factors influencing the distribution and abundance of the ticks as well as interactions with other species and the role of predators and pathogens are discussed.

Amitraz at a concentration of 2 ml litre-1 of water successfully induced detachment of Amblyomma marmoreum and Amblyomma hebraeum ticks from the mountain tortoise, Geochelone pardalis. Detached ticks died without reattaching. At the strength used, amitraz had no apparent adverse effects on the tortoises.

Domestic stock on a farm 30 km north of Grahamstown were treated with an acaricide at regular intervals over a period of several years. This resulted in a marked reduction in all stages of development of Amblyomma hebraeum on kudu (Tragelaphus strepsiceros), scrub hares (Lepus saxatilis) and helmeted guinea fowl (Numida meleagris) which were on the farm compared with the burdens of similar animals in an adjacent nature reserve. The populations of free-living larvae of A. hebraeum on this farm and on another farm 10 km south of Grahamstown, on which the domestic stock were also regularly treated with acaricides, were markedly reduced when a comparison was made with the free-living populations in the adjoining nature reserves.

Reproductive interference between three species of reptile tick, Aponomma hydrosauri, Amblyomma albolimbatum and Amb. limbatum was investigated. Adults of two species attach together on the same lizard hosts in narrow overlap zones at parapatric boundaries between species, providing opportunities for interference. The possibility of reproductive interference was suggested because of similarities in the sexual communication systems.Three forms of interference were found in laboratory experiments. Firstly male movement to search for sexually receptive females was inhibited when females of two species were present on the same host, probably because of signal interference. Secondly, a nonspecific, short range attractant pheromone led males into non-conspecific courtship attempts which reduced the time for conspecific courtships. Thirdly Amb. albolimbatum males physically blocked the genitalia of female Ap. hydrosauri after unsuccessful non-conspecific courtship attempts. Field data showed this behaviour was common in both Amblyomma species after conspecific matings. Reproductive interference would reduce the fitness of each species in sympatry, and may contribute to the maintenance of the narrow parapatric boundaries.

A comparison of attachment, engorgement and moulting success of Amblyomma hebraeum larvae fed on domestic chickens and Himalayan giant white rabbits indicates that chickens are better hosts than the rabbits. Moreover the time needed for detachment of all engorged larvae is significantly less for chickens than for the rabbits. No evidence of induced immunity was found in chickens on re-infestation with larvae of A. hebraeum.

The success of natural infestations of various life history stages of Amblyomma hebraeum and Amblyomma marmoreum on the leopard tortoise, Geochelone pardalis, was compared. Success was measured by the time taken for ticks to detach, as well as the percentage of ticks engorging and subsequently either moulting to the next life history stage or laying viable eggs. Larvae of A. hebraeum were the only developmental stage not recovered. Nymphae and female A. hebraeum were less successful in moulting or laying eggs than the corresponding stages of A. marmoreum. Nevertheless, 48,7% of A. hebraeum nymphae moulted, while 1 of 6 females laid viable eggs.

Striped mice, Rhabdomys pumilio, were trapped over a 17 month period in the Thomas Baines Nature Reserve in the eastern Cape Province of South Africa. Captured mice were placed in cages, over water, and naturally detaching ticks were collected. Only 5 larvae and 1 nymph of Amblyomma hebraeum were recovered from the mice. These represented less than 0.1% of the total number of ticks recovered. No Amblyomma marmoreum were recovered. As the vegetation and large mammals and tortoises in the Thomas Baines Nature Reserve abound in larvae of both these vectors of heartwater the low infestation rates of R. pumilio indicate that it is either unsuitable or inaccessible for these ticks. R. pumilio is therefore unlikely to play a role in the epidemiology of heartwater.

Large numbers of birds, wild mammals and domestic stock from a variety of localities within the Republic of South Africa were examined for infestation with the ixodid ticks Amblyomma hebraeum and Amblyomma marmoreum. Every warthog (Phacochoerus aethiopicus), Burchell's zebra (Equus burchelli), impala (Aepyceros melampus) and kudu (Tragelaphus strepsiceros) from the Kruger National Park in the north-eastern Transvaal Lowveld was infested with A. hebraeum. In the eastern Cape Province every helmeted guinea fowl (Numida meleagris), scrub hare (Lepus saxatilis) and kudu from the Andries Vosloo Kudu Reserve; all but 1 of the 22 domestic cattle examined on the farm "Bucklands"; and all Angora goats plus nearly all Boer goats examined on the farm "Brakhill" were infested with this tick. Most animals examined appeared to be good hosts of the immature stages, and the larger the host species the greater the chances of it harbouring large numbers of adult ticks. The largest animals examined, such as eland, buffalo, giraffe and rhinoceros, harboured very large numbers of adult A. hebraeum. No adult A. marmoreum was recovered from any host. However, 50% or more of helmeted guinea fowl and kudu from the Andries Vosloo Kudu Reserve; helmeted guinea fowl, scrub hares and eland (Taurotragus oryx) from the Mountain Zebra National Park; helmeted guinea fowl, kudu, domestic sheep, goats and cattle on the farm "Bucklands", and caracal (Felis caracal) from the Cradock and Southwell areas of the eastern Cape Province were infested with immature A. marmoreum. In the Bontebok National Park in the south-western Cape Province more than 35% of scrub hares, vaal ribbok (Pelea capreolus) and bontebok (Damaliscus dorcas dorcas) were infested with immature ticks.

Non-specificity of part of the sex pheromone system of three species of reptile tick has previously been suggested to result in reproductive interference between the species when they attach to the same host (Andrews et al. 1982). Two of the species, Aponomma hydrosauri and Amblyomma limbatum, have common aggregation pheromones which act when the ticks are detached from their hosts. As each species tends to occupy spatially separated microhabitats, the similarity of the aggregation pheromone could lead to interference between species when off their hosts by inducing one species to move away from its preferred microhabitat into that occupied by the other species. This study demonstrates that coaggregations of both species do occur, but that neither species shows a statistically significant shift in microhabitat preference attributable to interactions between species. We suggest that the behaviours leading to microhabitat choice in each species override the influence of the common aggregation pheromone.