Acari Metastigmata
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Acari Metastigmata
Introduction
The ticks are a small group of acarines under the suborder Metastigmata, also known as Ixodids.-They occur throughout the world, but are more frequently encountered in tropical and subtropical realms.
The Metastigmata is a small group in comparison to othe .. acarine suborders, comprising approximately 800 species from all over the world. They are grouped into three families, the Argasidae or soft ticks, Ixodidae or hard ticks and Nuttalliellidae (known only from Africa).
The ticks show morphological characters typical of other acari, but their peculiarities and greater size (2,000 to over 30,000 J.1.In) clearly distinguish them from most other acarines. Besides, there are certain characters which are present and distinct throughout the ontogeny of ticks. A hypostome armed with retrorse teeth serves to anchor the tick to its host A complex sensory setal field, Haller's organ, is located on the dorsal side of tarsQs-I iii all postembryonic stag~, providing sites for contact or olfactory chaemoreception. Other distinguishing features are : a pair of stigmata situated posterior to coxa IV or dorsal to coxa fiI-IV, palp with only three or four segments,
.chelic~ra 2.,.segmented, digits of chelicerae working in horizontal plane with their dentate faces directed externally.
The differences between the families extend to their structure as well as to their habits. The argasid ticks are non-scutate with leathery integument and capitulum inferior iIi the nymphs and adults, sexual dimorphisini slight, spiracles small and anterior to coxa-IV and pads, porose areas and festoon absent. The ixodid ticks are scutate with terminal capitulum, sexual dimorphism well marked, spiracles posterior to coxa-IV and pads, porose areas and festoon present.
The licks live as ecto parasites of vertebrates and feed obligatorily on the blood of mammals, reptiles and birds. Some of them are significant pests of man and animals in temperate forests, steppe and prairie habitats, as well as in the harsher tundra of the far north. In temperate and tropical countries, they surpass all other arthropods as transmitters in the number and variety of diseases of man and domestic animals. They cause paralysis and anemia and serve as reserviors and vectors for many infective viruses, rickeu.sias, bacteria, sporozoans and spirochaetes. Ticks are the main vectors of Kyasanur forest disease in man and monkeys in Karnataka state. Other arboviruses like Kaisodi, Ganjam and Bhanja are also isolated from ticks• in India. Ticks are oviparous. The life history passes through egg, larva, nymph and adult stages.
Historical Resume
The ticks attracted the attention of scientists since the days of Linnaeus ( 1746-.}767 ). Later, d~e to their immense medical importance, the progress in the field of taxonomy was made rapidly and culminated in a large number of papers and monogmphs by such authorities as Cooley ( 1909¬1945 ), kohls ( 1930-1969 ), Delpy ( 1934-52 ), Pomerantzev ( 1934-1950 ), Roberts ( 1934¬-1970), Theiler ( 1941-1964 ), Anastos ( 1947-1968 ), lioogstraal ( 1950-1985 ) and others. In the field of biology, experimental physiology and tick ecological technique, we owe much to the notable workers like Philip ( 1931-1969 ), Macleod ( 1932-1962 ,), Gregson ( 1935-1969 ), Hitchcock ( 1943-.55 ), Milne (.1943-1952), Lees ( 1945-1956) and Wilkinson ( 1953-1969 ).
The Indian ticks were taken up for research as early as in 1758. Since then they have been studied extensively in different aspects. The important works done on the families of Indian ticks are summarised below.
Classified Treatment
Family Ixodidae Linnaeus ( 1758) described Acarus elephantinus from India. Later in 1967, he described another Indian species Acarus indus. Neumann (1897-1910) in series of papers described ten species from India. Stiles alid Hasall (1899) recorded Boophilus australis for the rust time from India. Warburton and Nuttall (1908, 1909) described two species. In 1911 and 1915 theses two •workers alongwith Robinson and Cooper published two comprehensive works. entitled 'Ticks: A monograph of Ixodoidea' Part 2 and Part 3, dealing with the genera Ixodes and Haemaphysalis, in which two species were recorded for the rust time from India. Besides the monographs, Nuttall (1912, 1913, 1916) described two species from Uttar Pradesh and Arunachal Pradesh and recorded one m9re species from Kashmir Valley. The fourth volume of the book was published by Robinson (1926).
The most extensive and comprehensive study of Indian ixodids was done by Sharif (1928). He listed the Ixodidae occurring in India and recorded altogether 9 genera and 45 species, 4 subspecies and 6 varieties. He also provided informations on the bionomics of Hyalomma aegypticum. Further in 1938, Sharif reported diseases transmitted by the Indian ticks and the possibility of their control through biological agents. Sen (1938) published a check-list of Indian ixodid ticks and recorded 35 species under 9 genera from this subcontinent. Spare (1940, 1944) studied the biology of two species•.
After a long gap of about fifteen years, the Indian ixodids were again taken up seriously for research by the scientists at National Institute of Virology, Pune. Singh, Geevarghese, Sreenivasan, Misbra, Kaul, Dhanda, Bhat, Kulkarni, Rajagopalan and others (1964-1979) studied taxonomy, ecology and biology of ticks. They described and recorded several species from Uttar Pradesh, Arunachal Pradesh, Himachal Pradesh, Karnataka, Maharashtra, Tamil Nadu and West Bengal.
The Indian ixodid ticks were also extensively studied by Hoogstraal and his co-workers Trapido, Verma, McCarthy, Kohls, Rebello, Elkammah, Mitchell and others (1962-1971). Hoogstraal at the Medical Zoology Department, U.S. Naval Medical Research Unit number Three, Cairo (Egypt) and his co-workers studied the Indian ticks mostly of the genus Haemaphysalis collected by the staff members of National Institute of Virology, Pune. They described and recorded several species of ixodid ticks with their distribution and hosts from Bihar, Gujarat, Karnataka~ Uttar Pradesh, Kashmir, Rajasthan, Andhra Pradesh, Arunachal Pradesh, Sikkim, Himachal Pradesh and West Bengal. Advani and Vazirani (1981) recorded Ixodes vespertilionis as an ectoparasite of bat from Rajasthan.
The interrelationship between ixodid ticks and Kyasanur F.orest disease (KFD) virus resulting into the death of monkeys in a forested area of Shimog8: district, Karna~, was rust attended by Work and Trapido (1957). They published a preliminary report of investigations on the epidemic disease caused by KFD virus. Later Work (1958) added more informations on KFD. Trapido, Goverdhan, Rajagopalan and Rebello at National Institute of Virology, initiated a study on the qualiltative and quantitative aspects of the ticks ecto-parasitic on monkeys in the KFD area, during the period 1957 to 1961 and in 1964.
Bhat (1988) and Sreenivasan, Rajagopalan and Bhat (1988) studied the ecology of KFD virus and their isolation from ixodid ticks. In another attempt Dhar, B husan, Malhotra, Mallick and Gautam (1988) assessed Theileria annulata infection in Ilyalomma anatolicum anatolicum. In the same year Geevarghese and Dhanda (1988) studied the bionomics of three Indian species of Hyalomma ticks.
The study on Indian argasid ticks was started much later than the ixodids, and till date comparatively little work was done on this group of ticks. The rust report of Indian argasid
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Ornithodoros savignyi was made by Christophers (1906) from South India. Nuttall, Warburton, Cooper and Robinson (1908) recorded Argas persicus from Punjab, Maharashtra, Bihar, Andhra Pradesh and Uttar Pradesh. After a long gap of more than a decade, Cross and Patel (1922) recorded ArgaspersiclL.~. Ornithodoros lahorensis and O. savignyi from Punjab. Naik (1935, 1938) reported 'the occurrence of O. savignyi from Kamataka and Maharashtra. The second record of argasid from Punjab was done by Sen (1935). He made an extensive study on feeding mechanism of Ornithodoros papillipes (= O. tholozani). Kingston (1936) reported Otobius megnini as the frrst record of argasid tick from Madhya Pradesh. Sen (1938) published a check-list'and host index of 5 species and 3 genera of argasid ticks occurring in India, where he also recorded additional distribution data. Sharif (.1938) stated that Argas reflexus indicus was an important parasite of pigeons all over India. Joshi (1943) reported O. savignyi from Rajasthan.
Hoogstraal, the pioneer worker on Indian ticks, and his associates McCarthy, Kaiser and Kohls (1956-1968) described two new species Argas (Persicargas) abdussalami and A. (P.) robertsi, and also reported Argas (C.) vespertilionis and Ornithodoros (Alectorobius) coniceps for the frrst time from India. S.en and Fletcher (1962) extensivesly studied the argasid ticks of Punjab, Gujarat and Madhya Pradesh. They reported Ornithodoros (Pavlovskyella) tholozani and O. (P.) savignyi. Later Dhanda and Rajagopalan ( 1971 ) described a new species Ornithodoros (R.) chiropterphila from Karnataka. In the same year Rau and Rao (1971) described another new species Ornithodoros (0.) indica from Arunachal Pradesh. Besides taxonomic investigations, several other works related to ecology, biology and disease relationship were done by a few acarologists.
The most important of these are the studies of Rajagopalan, Paul'and Sreenivasan (1969) who studied the transmission of KFD virus by O. (R.) chriopterphila and the studies on the life cycle of O. megnini done by Jagannatb and Lokesh (1988).
The researches on Indian ticks in Zoological Survey of India was started by M. Sharif (1924¬1938 ). He worked on ixodid and argasid ticks of India as mentioned earlier. After Sharif there was no significant work untill Mathai (1951-1963) who described two species of ixodid ticks from India. Subsequently De started researches on this group. He published in 1976 a detailed report on ixodid ticks of Orissa. De, Sanyal and Gupta (1978-1990) have extensively surveyed the ixodid tick fauna of Arunachal Pradesh. Andaman and Nicobar Islands, Orissa, Uttar Pradesh, Tripura, Megbalaya and West Bengal and recorded several species for the fust time from these states. Basu, De and Sanyal (1989) reported the tick fauna associated with cattle and buffaloes in West Bengal.
In last few years (1983-1987) the staff of Acarology Section of Z.Sl. have extensively surveyed the ixodid fauna in all districts of West Bengal, collecting hundreds of specimens, and a monograph is under publication.
The studies on argasid ticks in Zoological Survey of India was done by Advani and Vazirani, at the Desert Regional Station, Jodhpur. They (1981) made an exhaustive work on the ectoparasites of bats in India. While doing this, they encountered a good number of tick specimens belonging t<;>both the families Ixodidae and Argasidae. The ixodid ticks collected from Rajasthan were identified as Ixodes vespertilionis. Of the six argasid species reported five were new to science Argas (Carios) soneshinei from Dadra and Nagar Haveli, A. (C.) indicus and A. (Chiropteragus) wilsoni from Rajasthan, A. (C.) gujaratensis, A. (C.) hoogstraali from Gujarat, and one species A. (C.) vespertilionis was added to the faunal list of Rajasthan.
Areas Yet To Be Explored
Although extensive surveys have been undertaken for collection of disease causing species, it is high time to study the tick fauna of economic importance. Further, studies on ecology and biology of Indian ticks need attention. The survey of tick fauna in many of the Indian States has not been done extensively.
Estimation of Taxa
Till date 86 species of ixodid ticks under 9 genera, and 21 species of argasid ticks under 3 genera occur in India. Nearly 33% of tick species are recorded from Kamataka and 30% from West Bengal. The other states represent a lesser number.
As already mentioned, the ixodid ticks are rich both in quality and quantity in comparison to argasid ticks. However, it is assumed that the chances of getting new species under Ixodidae are very little, while a thorough and extensive survey may add a few new and interesting species of Argasidae to the list of Indian tick fauna.
Current Studies
The scientists of Zoological Survey of India are presently studying the taxonomy of ixodid ticks of West Bengal, Tripura, Meghalaya and Uttar Pradesh. Outside ZSI, scientists in the National Institute of Virology, Pune, are extensively studying the taxono'my, ecology and biology of ixodid ticks.
Expertise India
In ZSI
A. K. Sanyal & S. K. De, ZSI, M-Block,-New Alipur, calcutta -700 053.
Elsewhere
H. R. Bhat, Vijay Dhanda, Stan Fernandes, G. GeeVarghese, H. N. Kaul, P. K. Rajagopalan, &M. A. Sreenivasan, all of National Institute of Virology, 20A, Ambedkar Road, Pune-411 001 (Maharashtra).
M. S. Jagannath, Department of Parasitology, Veterinary College, Bangalore -560 015 (Kamataka).
Sushovan Roy, Assistant Professor, Department of Medicine, College of Vety. Sci. & A. H., Durg (Post Box No.6) -491001 (Madhya Pradesh).
Abroad
Walter Auffenberg, Curator (Herpetology), Department of Natural Sciences, The Florida State Museum, University of Florida, Museum Road, Gainesville 32611, 904/392 -1721 (USA).
E. Burris, Department of Entomology, Oklahoma State University, Stillwater, Oklahama ¬74074 (USA ).
A. K. Basu, Faculty of Veterinary Medicine, University of Maiduguri, Maiduguri. (Nigeria).
Frantisek Dusbabek, Institute of Parasitology, Czechoslovak Academy of Sciences, Branisovska 31, 37005, Ceske Budejovice (Czechollovakia).
Zai-jie Jiang, Deparunent of Biology, Beijing Nonnai University, Beijing (China).
H. L. Keegan, The University of Mississippi Medical Center, 2500 North State Street, Jackson, Mississippi 39216 (USA).
G. M. Kohls, Rocky Mountain Laboratory, U.S. Public Health Service, Hemilton, Montana 59840 (USA).
Arndt Liebisch, Institute of Parasitology, Bunteweg 17, 3000 Hannover 71 (Germany).
M. Nadchatram, Division of Acarology, Institute Penyelidikan Perubatan, (Institute for Medical Research), Jalan Pakang, Kualalumpur 02-14, -(Malaysia).
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Selected References
Advani, R. &Vazirani, T. G. 1981. Studies on ectoparasites of bats of Rajasthan and Gujarat (India). Rec. zool. Surv. India, Occ. Paper no. 22 : 1-155.
De, S. K. &Sanyal, A. K. 1984. Ixodid tick (Acarina: Metastigmata) fauna of Andaman and Nicobar Islands. Bull. zool. Surv. India, 6 (1) : 59-64.
Geeverghese, G. &Dhanda, V. 1987. The Indian Hyalomma Ticks (Ixodoidea: Ixodidae). I.C.A.R., New Delhi: 1-119.
Nuttall, G. H. F. &Warburton, C. 1911. Ixodidae. Part 2, Section I. Classification. Section II. The genus Ixodes: (i) -xix, 105-348, In : Nuttall et al., Ticks. A Monograph of the Ixodoidea.
Nuttall, G. H. F. &Warburton, C. 1915. The genus Haemaphysalis. Part 3. : (i)-xiii, 349-550, In : Nuttall et al., Ticks. A Monograph of the Ixodoidea.
Nuttall, G. H. F., Warburton, C., Cooper, W. F. &Robinson, L. E., 1908. Ticks. A Monograph of the Ixodoidea. Part I, Section I. Classification of Argasidae. Section II. Biology of Argasidae: (i)-x, 1-104.
Robinson, L. E. 1926. The genus Amblyomma. vol. IV, In Nuttall et al., Ticks. A Monograph ofthe Ixodoidea: 302 pp.
Sanyal, A. K., De, S. K., Rao, A. T. &Acharjyo, L. N. 1987. Acarina: Metastigmata (Ticks). In : Fauna of Orissa: State fauna Series, No.1, Pt.! : 273-287. Z.S.I., Calcutta.
Sen, P. 1938. A check and host-list of Ixodoidea (ticks) occurring in India. Indian J. Vet.Sci.,8
(2) : 133-147.
Sharif, M. 1928. A revision of the Indian Ixodidae, with special reference to the collection in the Indian Museum. Rec. Indian Mus., 30 ( 3 ) : 217-344.
