A Review of the Ticks (Acari, Ixodida) of Brazil, Their Hosts and Geographic Distribution - 1. The State of Rio Grande do Sul, Southern Brazil
Vol. 95(4): 453-470, Jul./Aug. 2000
DE Evans/+, JR Martins*, AA Guglielmone**
Departamento de Parasitologia Animal, Instituto de Biologia, Universidade Federal Rural do Rio de Janeiro, 23890-000 Seropédica, RJ, Brasil *Centro de Pesquisa Veterinária Desidério Finamor, Caixa Postal 47,
92990-000 Eldorado do Sul, RS, Brasil **Estación Experimental Agropecuaria Rafaela, Instituto Nacional de Tecnologia Agropecuaria, Casilla Correo 22, CP 2300 Rafaela, Santa Fé, ArgentinaA review of the ticks (Acari, Ixodida) of the State of Rio Grande do Sul, southern Brazil, was completed as a step towards a definitive list (currently indicated as 12) of such species, their hosts and distribution. The ticks: Argas miniatus (poultry), Ixodes loricatus (opossums), Amblyomma aureolatum (dogs), A. calcaratum (anteaters), A. cooperi (capybaras), A. nodosum (anteaters), A. tigrinum (dogs) (Neotropical) and Rhipicephalus sanguineus (dogs) (introduced, cosmopolitan, Afrotropical) were confirmed as present, in addition to the predominant, Boophilus microplus (cattle) (introduced, pan-tropical, Oriental). Of the further 18 species thus far reported in the literature as present in the state, but unavailable for examination: only Ornithodoros brasiliensis (humans and their habitations) (Neotropical), Ixodes affinis (deer) (Nearctic/Neotropical) and I. auritulus (birds) (Nearctic/Neotropical/Afrotropical/ Australasian) are considered likely; 13 species would benefit from corroborative local data but the majority appear unlikely; reports of A. maculatum (Nearctic/Neotropical, but circum-Caribbean) are considered erroneous; the validity of A. fuscum is in doubt. The very recent, first known report of the tropical Anocentor nitens (horses)(Nearctic/Neotropical), but still apparent absence of the tropical A. cajennense (catholic) (Nearctic/Neotropical) and the sub-tropical/temperate Ixodes pararicinus (cattle) (Neotropical) in Rio Grande do Sul are important for considerations on their current biogeographical distribution and its dynamics in South America. The state has relatively long established, introduced ("exotic"), Old World tick species (B. microplus, R. sanguineus) that continue to represent significant pests and disease vectors to their traditional, introduced domestic animal hosts, cattle and urban dogs. There are also indigenous, New World ticks (A. miniatus, O. brasiliensis, A. aureolatum, A. nitens), as both long established and possibly newly locally introduced species in the state, that should be considered as potential and emergent pests and pathogen vectors to humans and their more recently acquired, introduced domestic animal hosts; rural poultry, dogs and horses.
Key words: tick species - Ixodida - Rio Grande do Sul - Brazil
Attention to the pan-tropical cattle tick, Boophilus microplus, (Oriental) in the State of Rio Grande do Sul, Brazil, has been extensive due to its considerable economic importance there (estimated losses, 1983, in excess of US$130 million/year; Horn 1985), in common with other sub-tropical and tropical areas of the world into which it has been introduced by man (Hoogstraal 1973a, Sutherst & Maywald 1985). The problem has been exacerbated in the state by the local tradition of the predominant use of highly tick susceptible Bos taurus breeds of cattle, averaging between 12-13 million head for beef as well as some dairy production. Only in recent years have there been some trends to crossbred cattle, involving the inclusion of more tick resistant B. indicus, although not always directly for reasons of improved tick control (Norton & Evans 1989). Thus B. microplus continues to merit priority of attention in research, development, training and extension activities in the state (Evans 1984, 1992a, Evans & Arteche 1984). This is especially in attempts to improve the efficiency of its control or, ideally, prevention of its direct debilitating effects as well as its transmission of the causal agents of bovine babesiosis and anaplasmosis (Martins & Corrêa 1995). The repeated ability of this tick to develop resistance to the compounds used as acaricides in its chemical control (Laranja et al. 1988, 1989, Martins et al. 1995b, Farias 1999) stresses the continuing need to fully understand its ecology, physiology and epidemiology (Evans 1989, 1992b). Such knowledge enables the design of practical integrated strategies against the tick and its transmitted diseases in Rio Grande do Sul (Evans 1984, Alves-Branco et al. 1989, Martins et al. 1994, 1995a, Anon 1995, 1998, Kessler & Schenk 1998) and elsewhere.
No extensive review of the state's tick fauna, other than B. microplus on cattle, has been attempted since the work of Pinto and Di Primio (1931), Corrêa (1948, 1955) and the series of Freire (1943, 1958, 1967a, 1967b, 1968, 1972) that terminated more than a quarter of a century ago. This is in spite of more recent reports of various tick species in the state (Silva & Gonzales 1972, Oliveira 1973, 1994, Gonzales & Oliveira 1994, Martins & Guglielmone 1995, Sinkoc et al. 1995, 1997), some corrections to previous mis-identifications (Guglielmone et al. 1982) and even reports of two new tick species in the surrounding geographic region (Keirans et al. 1985, Guglielmone et al. 1990). Rio Grande do Sul also forms part of a biogeographical transition zone between tropical and sub-tropical regions of SE South America, with expected similar transitions of tick species' natural distributions and those due to human activities.
There is currently a greatly renewed interest in tick species that parasitise other domestic stock, pets, wildlife and especially man himself to enable their greater protection. Highly economically or emotionally valued animals are receiving more attention from their owners. Modern Brazil witnesses everincreasing contacts between man, pets, livestock and wildlife or their habitats and thus their ticks, so increasing the chances of acquisition of the irritations, toxicoses and anaemias they may cause and the pathogens they may transmit. The last major biogeograhical review of the ticks of Brazil, however, is now almost 40 years old (Aragão & Fonseca 1961). It is wise to know exactly what one has locally so that the relevant veterinary and public health personnel can be as well informed as possible. Such knowledge should include possible changes in pest status or spread of indigenous (Mangold et al. 1986) and introduced ("exotic") (Ribeiro et al. 1997) tick species. The immediate recognition of any previously unrecorded species being "imported" or in the initial stages of their establishment is also vital to implement appropriate quarantine, eradication or control actions. Such periodic reminders (Aragão 1936, Corrêa 1955, Freire 1972) should not be ignored. Clearly, to permit any further, Rhipicephalus sanguineus or, perhaps worse, B. microplus-like introductions and establishment could prove similarly economically disastrous.
Based on the above concerns, we considered it opportune to initiate a review of the known tick fauna (other than of B. microplus on cattle), its biogeographical distribution and host relations in Brazil, in this case of its most southern state, Rio Grande do Sul. We list all reports of tick species, their hosts and locations in the state up to the present time and of unreported material of the authors and some colleagues. These data are also discussed in the light of other biogeographical works in the region. An attempt at a definitive list of tick species of the state, as known at this time, is offered, as is a host-parasite list for these species. It is hoped that further studies on these important obligate ectoparasites will be assisted and encouraged in this manner. The adopted format of reappraisal of information on the known ticks and their hosts on a state by state basis, in collaboration with local specialists, provides a means to achieve fully up-dated, locally applicable reviews in Brazil, that are currently non-existent. A series of such documented state investigations can also be accumulated to constitute the long overdue, national review of the Ixodida.
ACKNOWLEDGEMENTS
To Dr JF Amato, UFRGS, Porto Alegre, RS, for criticism of an early draft of the manuscript and helping us to define some of the reported locations in Rio Grande do Sul; Dr JLH Faccini, UFRRJ, Seropédica, RJ, for comments that led to several modifications to the paper; Dr CM Oliveira, UFRGS, Porto Alegre, RS, for the opportunity (for JRM) to examine his unique Rio Grande do Sul material of A. nodosum and his extremely generous permission (09/09/99) to us to include in this review the alarming first report of A. nitens in Rio Grande do Sul, identified by him and confirmed by DEE & JRM, from a collection by L Ferreiro (05/99) found on a horse in Viamão, RS; Drs AP de Souza, V Bellato and AA Sartor, Udesc, Lages, for permitting us (30/04/99 and 29/09/99) to include information from the most recent findings of their tick surveys throughout Santa Catarina, especially the first known report of A. cajennense from the state, identified by them from a collection by M Lenzi (09/99) from horses, cattle and as free-living stages in Itajaí, SC; Dr DM Barros-Battetsi, Curator, Tick Collection, Instituto Butanatan, São Paulo, SP, for personal access to unpublished records on Brazilian tick species at its Laboratório de Artrópodos (07/11/99), to check for any evidence of A. cajennense samples from Rio Grande do Sul.
The senior author was financially supported by the National Council for Scientific & Technological Development (CNPq) and subsequently by the Research Support Foundation for the State of Rio de Janeiro (Faperj), Brazil, during the completion of this review. Corresponding author: Estrada dos Bandeirantes 27635, Vargem Grande, 22785-090 Rio de Janeiro, RJ, Brasil. Fax: +55-21-437.8422. E-mail: davidericevans@openlink.com.br
Received 22 May 1999
Accepted 4 January 2000
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