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Mastozoología neotropical

versión impresa ISSN 0327-9383

Mastozool. neotrop. vol.17 no.2 Mendoza dic. 2010

 

ARTÍCULOS

Rodents Of The Subfamily Caviinae (Hystricognathi, Caviidae) As Hosts For Hard Ticks (Acari: Ixodidae)

Alberto A. Guglielmone and Santiago Nava

Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Agropecuaria Rafaela and Consejo Nacional de Investigaciones Científicas y Técnicas, CC 22, CP 2300 Rafaela, Santa Fe, Argentina [Correspondence: Santiago Nava <snava@rafaela.inta.gov.ar>].

Recibido 26 marzo 2010.
Aceptado 19 julio 2010.
Editor asociado: G Navone

ABSTRACT: There are only 33 records of rodents of the subfamily Caviinae Fischer de Waldheim, 1817 (Hystricognathi: Caviidae) infested by hard ticks in South America, where the subfamily is established. Caviinae is formed by three genera: Cavia Pallas, 1766, Galea Meyen, 1833 and Microcavia Gervais and Ameghino, 1880. Records of Amblyomma pictum Neumann, 1906, A. dissimile Koch, 1844 and A. pseudoparvum Guglielmone, Keirans and Mangold, 1990 are considered doubtful. Bona fide records are all for localities south of the Amazonian basin in Argentina, Bolivia, Uruguay and Brazil. Thirteen records are for A. tigrinum Koch, 1844, four for A. triste Koch, 1844, three for A. parvum Aragão, 1908 (larvae and nymphs of these three species), one for A. cajennense (Fabricius, 1787) (nymph), four for Ixodes longiscutatus Boero, 1944 (females, nymphs and larvae) and one record for I. loricatus Neumann, 1899 (female). Rodents of the subfamily Caviinae are vital for the life cycle of A. tigrinum and A. parvum and probably for A. triste and I. longiscutatus. It is hypothesized that Ixodidae precedes Caviinae in establishment in South America (Neotropical), therefore this host-relationship is relatively recent measured in evolutionary times starting in late Miocene or afterwards. Rodents of the subfamily Caviinae appears to be relevant for the life cycle and speciation of hard ticks in South America as shown by studies carried out in Argentina and Uruguay. This role has been hidden presumably because this type of hosts was ignored in most ecological tick studies performed in South America.

RESUMEN: Roedores de la subfamilia Caviinae como hospedadores para garrapatas duras (Acari: Ixodidae). Existen solamente 33 registros de roedores de la subfamilia Caviinae Fischer de Waldheim, 1817 (Hystricognathi: Caviidae) infestados por garrapatas duras en Sudamérica, donde la subfamilia está establecida. Caviinae está formado por los géneros Cavia Pallas, 1766, Galea Meyen, 1833 y Microcavia Gervais y Ameghino, 1880. Los registros de Amblyomma pictum Neumann, 1906, A. dissimile Koch, 1844 y A. pseudoparvum Guglielmone, Keirans y Mangold, 1990 son considerados dudosos. Registros fehacientes fueron realizados al sur de la Amazonia, en Argentina, Bolivia Uruguay y Brasil. Trece registros son para A. tigrinum Koch, 1844, cuatro para A. triste Koch, 1844, tres para A. parvum Aragão, 1908, uno para A. cajennense (Fabricius, 1787), cuatro para Ixodes longiscutatus Boero, 1944 y uno para I. loricatus Neumann, 1899. Los roedores de la subfamilia Caviinae son vitales para el ciclo biológico de A. tigrinum y A. parvum y probablemente también para A. triste e I. longiscutatus. La hipótesis planteada consiste en que Ixodidae precede a Caviinae en su establecimiento en Sudamérica, por lo tanto la formación de esta relación hospedador-parásito es relativamente reciente medida en tiempos evolutivos, con un comienzo no anterior al Mioceno tardío. De acuerdo a estudios realizados en Argentina y Uruguay, los roedores de la subfamilia Caviinae son relevantes en el ciclo biológico y en los procesos de especiación de garrapatas duras en Sudamérica. El papel de estos roedores en la evolución de garrapatas sudamericanas es subvalorado porque este tipo de hospedadores fueron ignorados en la mayoría de los estudios ecológicos de dichos ectoparásitos.

Key words. Amblyomma; Caviinae; Hosts; Ixodes; Ixodidae.

Palabras clave. Amblyomma; Caviinae; Hospedadores; Ixodes; Ixodidae.

INTRODUCTION

Rodents of the family Caviidae Fischer de Waldheim, 1817 are divided into three sub-families in Woods and Kilpatrick (2005): Caviinae Fischer de Waldheim, 1817, Dolichotinae Pocock, 1922 and Hydrochaerinae Gray, 1825. The Hydrochaerinae is formed by the genera Hydrochoerus Brisson, 1762 (two species) and Kerodon F. Cuvier, 1825 (two species), Dolichotinae has just one genera, Dolichotis Desmarest, 1820, with two species. Amblyomma dubitatum Neumann, 1899 is recognized by the preference of their immature and adult stages to feed on the capybara Hydrochoerus hydrochaeris (Linnaeus, 1766) as revised in Nava et al. (2010), while Amblyomma pseudoparvum Guglielmone, Mangold and Keirans, 1990 is prone to feed on Dolichotis salinicola Burmeister, 1876 (Guglielmone and Nava, 2006). However, there is no such obvious relationship of Caviinae with any tick species, although most species of Caviidae belong to Caviinae.
The subfamily Caviinae contains three genera: Cavia Pallas, 1766, Galea Meyen, 1833 and Microcavia Gervais and Ameghino, 1880. There appears to be consensus that Microcavia consists of three species, M. australis (Geoffroy and d'Orbigny, 1833), M. niata (Thomas, 1899) and M. shiptoni (Thomas, 1925) as presented in Woods and Kilpatrick (2005). Galea is generally considered to contain three species, G. flavidens (Brandt, 1835), G. musteloides Meyen, 1833, and G. spixii (Wagler, 1831), but recent work supports splitting G. musteloides into four species: G. comes (Thomes, 1919), G. leucoblephara (Burmeister, 1861), G. musteloides and a still unnamed species (Dunnum and Salazar-Bravo, 2010a). Controversy also exists for the genus Cavia; we follow Dunnum and Salazar-Bravo (2010b) that found this genus formed by six species: C. aperea Erxleben, 1777, C. fulgida Wagler, 1831, C. intermedia Cherem, Olimpo and Ximenez, 1999, C. magna Ximenez, 1980, C. patzelti Schliemann, 1982, and C. tschudii Fitzinger, 1857 (this last taxon was found to be the most certain origin of domesticated guinea pigs).
Species of Caviinae have an ample distribution in South America covering almost all continental land from 11º N to 53º S, with the exception of the Amazon basin. Cavia aperea has a disjunct distribution south and north of the Amazon separated by areas colonized by C. patzetli and especially C. tschudii in central-western South America. Other species of Cavia are concentrated in central-eastern South America. The southern limit of Cavia is about 39º S in Argentina for C. aperea. Galea is established from central Brazil-southern Peru to the Patagonia in Argentina with G. flavidens established in a small area of central Brazil, the rest of north-eastern distribution is covered by G. spixii. The G. musteloides species complex is established from southern Peru to Patagonia in Argentina as follows: G. comes in the Andes of southern Argentina and northern Bolivia; G. leucoblephara from Bolivian and Paraguayan lowlands to northern Patagonia in central Argentina, G. musteloides in highlands of northeastern Chile, southeastern Peru and northwestern Bolivia, while a still unnamed species of Galea is established at midlands of the Andes of southern Bolivia (Dunnum and Salazar-Bravo, 2010a). Microcavia is present from southern Bolivia to southern Argentina and Chile, with M. niata in south western Bolivia and northern Chile, M. shiptoni is established in a small area of north western Argentina, and the rest of the distribution is covered by M. australis.
Recent studies show that rodents of the sub-family Caviinae are of relevance for a few species of Ixodidae ticks (Nava et al., 2006a, b, 2008a, b, 2009; Venzal et al., 2008 b), but this subfamily has not been reviewed for his importance as host for hard-ticks species. A revision has been made to know the relationship between hard ticks and species of Caviinae under the hypothesis that its role on this host-parasite relationship is more relevant than shown in the poor historical records of tick feeding on members of this subfamily.

MATERIALS AND METHODS

Literature information of ticks feeding on Caviinae were registered considering the species of tick and host, stages of ticks, locality, coordinates, political division, country, reference and comments, when appropriate, for each record. Repeated records for same host, tick stages and locality were considered as one record even if they have different dates. References to Cavia pamparum (Thomas, 1901) were considered to be referring to C. aperea. Records on hosts with no specific determinations were tentatively given specific status if the locality was within the range of a given species with few chances of confusion with other member of the subfamily. All these inferences are included in the corresponding comment. Additionally, data from the Acari Collection from Instituto Butantan (IBSP), São Paulo, Brazil, were included. The ticks of IBSP were determined by the curator Darci M. Barros-Battesti following Martins et al. (2010).
A line of C. tschudii has been domesticated by Andean civilizations (Dunnum and Salazar-Bravo, 2010b); it is currently distributed worldwide and known under the name of "cobayo" or "guinea pig". Cobayos were used for many biological experiments, including laboratory rearing of several species of ticks. Exclusively South American records from natural populations are included in this revision.
Amblyomma maculatum Koch, 1844 has been confused with A. tigrinum Koch, 1844 or A. triste Koch, 1844 in Argentina where that species of ticks is not present (Ivancovich, 1980, Guglielmone et al., 1982). There are several records of A. maculatum on Caviinae for Argentina. They were considered to be A. triste if recorded in riparian localities where this species prevails, or A. tigrinum if not recorded in riparian localities where this species is unusually found (Guglielmone and Nava, 2006). Each of these records is commented.

RESULTS

Records of ticks on rodents of the subfamily Caviinae are listed below.

Cavia sp.

1)   Amblyomma pictum Neumann, 1906, male, Bonasika River, 06º45' N 58º30' W, Guayana, Guyana, Keirans (1985). This author has doubts about host identification. If confirmed it is probably C. aperea.
2)   Amblyomma tigrinum, tick stage unregistered, Valle Fértil (San Agustín del Valle Fértil), 30º37' S 67º27' N, San Juan, Argentina, Capri and Mauri (1971). The tick species was classified as A. maculatum. The Argentinean San Juan province is out of the current known distribution of Cavia and may belong to a species of Galea or Microcavia.
3)   Ixodes longiscutatus Boero, 1944, female, locality unknown, Uruguay, Keirans et al. (1976). The host may be C. aperea or C. magna, but lack of coordinates precludes any inference about which species is most probably the host for this specimen of I. longiscutatus. Keirans et al. (1976) named this tick as I. uruguayensis Kohls and Clifford, 1967.
4)   Ixodes longiscutatus, nymph, San Vicente, 35º02' S 58º25' W, Buenos Argentina, Venzal et al. (2008 b). The Caviinae involved in this record is probably C. aperea.
5)   Ixodes loricatus Neumann, 1899, female, Anápolis, 16º19' S 48º57' W, Goiás, Brazil, Fonseca and Aragão (1952). Probably the host is C. aperea. Fonseca and Aragão (1952) named this species as I. didelphidis Fonseca and Aragão, 1952.

C. aperea

6)   Amblyomma dissimile Koch, 1844, nymph, Reserva Biológica, 08º39' S 38º01' W, Pernambuco, Brazil, Botelho et al. (2002). These authors found nymphs of A. dissimile (a tick found mainly on Anura and Squamata) on Rodentia and Didelphimorphia, which is not unexpected considering that other authors also found this tick on mammals. However, the authors stated that the only tick found after two months of work and capture of 83 mam-mals recognized as hosts for several species of ticks, were exclusively A. dissimile. We consider that these records need confirmation.
7)  Amblyomma pseudoparvum, nymph and larva, Fuerte Esperanza, 25º02' S 61º55' W, Chaco, Argentina, Ivancovich and Luciani, (1992). These authors named the species as A. parvum Aragão, 1908, but the diagnosis of the larva and nymph of A. pseudoparvum are considered doubtful because they are previous to the description of these tick stages.
8)  Amblyomma tigrinum, nymph, Sierra de la Ventana, 38º00' S 62º00' W, Buenos Aires, Argentina, Capri and Mauri (1971). These authors classified the tick as A. maculatum.
9)  Amblyomma tigrinum, tick stage unregistered, locality unknown, Buenos Aires, Argentina, Castro et al. (1987).
10) Amblyomma triste, tick stage unregistered, Delta del Paraná, 34º12' S 58º51' W, Buenos Aires, Argentina, Boero (1954). This author determined the specie as A. maculatum.
11) Amblyomma triste, nymph and larva, INTA Delta del Paraná, 34º11' S 58º50' W, Buenos Aires, Argentina, Nava et al. (2008c).
12) Amblyomma triste, nymph and larva, Reserva Natural Otamendi, 34º12' S 58º51' W, Buenos Aires, Argentina, Nava et al. (2008c).
13) Amblyomma triste, nymph, locality unknown, Uruguay, Venzal et al. (2008 a).
14) Ixodes sp., tick stage unregistered, locality unknown, Department of Durazno, Uruguay, Vogelsang (1928).
15) Ixodes longiscutatus, larva, locality unknown, Uruguay, Venzal et al. (2003).

C. tschudii

16) I. longiscutatus, female, nymph and larva, Parque Nacional El Rey, 24º15' S 64º40' W, Salta, Argentina, Beldoménico et al. (2003).

Galea sp.

17) Amblyomma tigrinum, tick stage unregistered, Sierra de la Ventana, 38º08' S 61º47' W, Buenos Aires, Argentina, Castro et al. (1987). Most probably the host is G. leucoblephara as defined in Dunnum and Salazar-Bravo (2010a).

G. musteloides species complex

18) Amblyomma cajennense (Fabricius, 1787), nymph, Cuevo, 20º26' S 63º32' W, Chuquisaca, Bolivia, Fonseca (1959). The author indicates collection of "juvenile specimens". In fact, one of these ticks is deposited at the IBSP (collection number 3558) and corresponds to a nymph of A. cajennense. This host may correspond to G. leucoblephara Burmeister, 1861 as described in Dunnun and Salazar-Bravo (2010a).
19) Amblyomma tigrinum, nymph, Cuevo, 20º26' S 63º32' W, Chuquisaca, Bolivia, Fonseca (1959). The author indicates collection of "juvenile specimens". In fact, 9 of these ticks are deposited at the IBSP (collection number 3558) and correspond to nymphs of A. tigrinum. This host may correspond to G. leucoblephara Burmeister, 1861 as described in Dunnun and Salazar-Bravo (2010a).
20) Amblyomma tigrinum, nymph, Padilla, 19º18' S 64º18' W, Chuquisaca, Bolivia, Fonseca (1959). The author indicates collection of "juvenile specimens", under collection number IBSP 3564, but in fact there are two nymphs mounted on slides. This host may correspond to G. leucoblephara as described in Dunnun and Salazar-Bravo (2010a).
21) Amblyomma tigrinum, nymph, Charagua, 19º47' S 63º13' W, Santa Cruz, Bolivia, Fonseca (1959). The author indicates collection of "juvenile specimens", under collection number IBSP 3559, but the material comprises 15 nymphs of A. trigrinum. This host may correspond to G. leucoblephara as described in Dunnun and Salazar-Bravo (2010a).
22) Amblyomma tigrinum, nymph, Vale Grande, 18º29' S 64º06' W, Santa Cruz, Bolivia, Fonseca (1959). The author indicates collection of "juvenile specimens", under collection numbers IBSP 3553 and IBSP 3556. There are 7 nymphs and 4 nymphs in bothlots, respectively. This host may correspond to G. leucoblephara as described in Dunnun and Salazar-Bravo (2010a).
23)  Amblyomma sp. nymph and larva, Tarija, 21º31' S 64º44' W, Tarija, Bolivia, Fonseca (1959). The author indicates collection of "juvenile specimens", under collection numbers IBSP 3561. Unfortunately this material is lost according to the curator of the IBSP. It is uncertain if this host corresponds to G. leucoblephara or to a still unnamed species of Galea as described in Dunnun and Salazar-Bravo (2010a).
24) Amblyomma parvum, nymph and larva, Campo La Esperanza, 30º12' S 64º31' W, Córdoba, Argentina, Guglielmone et al. (2007). This host corresponds to G. leucoblephara as presented in Dunnun and Salazar-Bravo (2010a).
25) Amblyomma parvum, nymph and larva, Campo Los Socavones, 30º12' S 64º34' W, Córdoba, Argentina, Guglielmone et al. (2007). This host corresponds to G. leucoblephara as presented in Dunnun and Salazar-Bravo (2010a).
26) Amblyomma parvum, nymph and larva, Quilino, 30º12' S 64º31' W, Córdoba, Argentina, Nava et al. (2008a). This host corresponds to G. leucoblephara as presented in Dunnun and Salazar-Bravo (2010a).
27) Amblyomma tigrinum, nymph and larva, Campo La Esperanza, 30º12' S 64º31' W, Córdoba, Argentina, Guglielmone et al. (2007). This host corresponds to G. leucoblephara as presented in Dunnun and Salazar-Bravo (2010a).
28) Amblyomma tigrinum, nymph and larva, Campo La Luisiana, 30º22' S 64º23' W, Córdoba, Argentina, Guglielmone et al. (2007). This host corresponds to G. leucoblephara as presented in Dunnun and Salazar-Bravo (2010a).
29)  Amblyomma tigrinum, nymph and larva, Campo Los Socavones, 30º12' S 64º34' W, Córdoba, Argentina, Guglielmone et al. (2007). This host corresponds to G. leucoblephara as presented in Dunnun and Salazar-Bravo (2010a).
30) Amblyomma tigrinum, nymph, Salta, 24º47' S 65º24' W, Salta, Argentina, Aguirre et al. (2005). It is uncertain if this host corresponds to G. musteloides-leucoblephara or to G. comes Thomas, 1919 as described in Dunnun and Salazar-Bravo (2010a).
31) Amblyomma sp., tick stage unregistered, Tornquist, 38°06' S 62°10' W, Buenos Aires, Argentina, Rood (1972). This host corresponds to G. leucoblephara as presented in Dunnun and Salazar-Bravo (2010a).

Microcavia australis

32) Amblyomma sp., tick stage unregistered, 40 Km north-east of Carmen de Patagones, 40°36' S 62°38' W, Buenos Aires, Argentina, Rood (1972).

"Wild cavy"

33) Amblyomma tigrinum, nymph?, Algarrobo, 38º53' S 63º08' W, Buenos Aires, Argentina, Voltzit (2007). Adults reared most probably from engorged nymphs fed on the "wild cavy", but not stated in Voltzit (2007). This author appears to locate this finding in Pampa (=La Pampa) province, but the locality belongs to the Province of Buenos Aires. The host may be either G. leucoblephara as presented in Dunnun and Salazar-Bravo (2010a) or M. australis.
The distribution of records is concentrated south of the Amazonian basin with 32 records (20 from Argentina, 6 from Bolivia, 4 from Uruguay and 2 from Brazil) and one report north to the basin in Guyana, but the author registered doubts about the identification of host parasitized with A. pictum (Keirans, 1985).
The records for Bolivia include Amblyomma sp., A. cajennense and A. tigrinun, a record for Uruguay corresponded to an undetermined species of Ixodes, while the record of nymphs of A. dissimile and larvae and nymphs of A. pseudoparvum on C. aperea by Botelho et al. (2002) and Ivancovich and Luciani (1992), respectively, are considered doubtful. There-fore, bona fide records of Caviinae as hosts for recognized species of ticks are (all south to the Amazonian basin) as follows: 1 record of A. cajennense (nymph), 13 records of A. tigrinum (larvae and nymphs), 4 records of A. triste (larvae and nymphs), 4 records of I. longiscutatus (females, nymph and larvae), 3 for A. parvum (larvae and nymphs) and 1 record of I. loricatus (female).

DISCUSSION

The scarcity of historical records of Ixodidae feeding on Caviinae is notorious apparently supporting the view of the irrelevance of this subfamily for Neotropical hard-tick life-cycles. Ixodes loricatus is recognized usually as a parasite of Neotropical marsupials and cricetid rodents (Nava et al., 2004) and, eventually, this species has been found on other mammals (Arzua et al., 2005) but not on Caviinae. Therefore, the biological significance of members of Caviinae as host of I. loricatus remains obscure. Ixodes longiscutatus presents a disjunct distribution with allopatric populations, one in Uruguay and neighboring Argentinean provinces, the other in northwestern Argentina. This species is peculiar forming the monotypic subgenus Haemixodes Kohls and Clifford, 1967 that appears to represent a different lineage of Neotropical Ixodes (Venzal et al., 2008 b), showing its importance for tick evolution in this Zoogeographic Region. Although larva and nymphs of I. longiscutatus have been found on Caviinae most records are from cricetid rodents. Adult ticks are just known for a total of six females, three of them were collected from cattle and horses which are obviously not the primeval host for this species, and the rest were found on Cavia sp., (probably C. aperea) in Uruguay and C. tschudii in northwestern Argentina. Indeed, additional work is needed to understand the ecology of I. longiscutatus, but again the role of Caviinae seems to be of importance in its life cycle.
Different is the situation when analyzing the relationship of Caviinae with the remainder species of ticks found on them. The presence of a nymph of A. cajennense on a species of Galea from Bolivia is not unexpected because immature stages of this tick species were observed parasitizing marsupials and rodents of the families Cricetidae, Echimyidae, Chinchillidae, Dsyproctidae and Myocastoridae (Ivancovich and Luciani, 1992; Estrada-Peña et al., 2004).
Studies in Argentina on the ecology of A. tigrinum and A. parvum showed a crucial role of G. leucoblephara (named as G. musteloides) for the life cycle of both ticks. Amblyomma tigrinum is peculiar for its ability to colonize areas with contrasting climatic conditions; adult ticks are prone to infest wild and domestic Canidae (Nava et al., 2006b). Ground feeding birds were found to harbor infestations with larvae and nymphs of A. tigrinum, but most larvae were found feeding on cricetid rodents and most nymphs (83%) were detected on G. leucoblephara (Nava et al., 2006b). This species is infested throughout the year with A. tigrinum nymphs showing peaks of median infestations ranging for 9 to 20 nymphs per host (Nava et al., 2009). Moreover, records from Bolivia and northwestern to central Argentina showed that Caviinae were hosts for sub-adults A. tigrinum beyond the area of study of Nava et al. (2006b, 2009) as presented in the Results section of this article, indicating a wide role as host for the immature stages of this tick. Finally, research in progress on the ecology of A. triste show that C. aperea is a relevant host for larvae and nymphs along with cricetid rodents (S. Nava, unpublished).
Amblyomma parvum is a Neotropical species with a partly surrogate host-parasite relationship depending on adults feeding on domesticated mammals, especially Bovidae, recently introduced into the Neotropics (Nava et al., 2006a). Birds, cricetid rodents and G. leucoblephara (named as G. musteloides) were evaluated by monthly sampling to determine their role as hosts for larvae and nymphs of A. parvum in Central Argentina. The result was conclusive, 99.3% and 99.8% of larvae and nymphs, respectively, were found on G. leucoblephara (Nava et al., 2006a, 2008a) presenting another evidence of the importance of Caviinae as host for Neotropical Ixodidae.
The Ixodidae family is formed by the Prostriata (genus Ixodes) and Metastriata (all genera apart of Ixodes) groups, and there is consensus among tick workers that Prostriata is basal. Rock evidence shows earliest emergence of Metastriata 100 mya (Cretaceous) (Grimaldi et al., 2002) indicating a more ancient evolution of Prostriata, being almost certain that Ixodidae preceded Caviinae in colonizing South American niches. South American Rodentia has an African origin close to the Eocene-Oligocene boundary (ca. 34 mya), but Caviinae arose later as shown by the origin of Galea and Cavia in late Miocene (ca. 10 mya for Galea and 6 mya for Cavia) (Dunnum and Salazar-Bravo, 2010a, b). There-fore, it is considered that the relationship Caviinae-Ixodidae is relatively recent measured in evolutionary times (this is also true for the relationship of Cricetidae and Ixodidae in the Neotropics). Tick feeding strategy of A. tigrinum with adults nourishing on Canidae, a predator of Cricetidae and Caviinae which harbor most larvae and nymphs of this tick, is also rather recent considering the introduction of Canidae into South America occurred in Late Pliocene (ca. 3 mya) (Prevosti and Pardiñas, 2009). The same will be true for I. longiscutatus if confirmed that this species depends on Caviinae and Cricetidae for its life cycle.
In any situation, Caviinae play a relevant role for life cycle and probably speciation of hard ticks. We hypothesized that this role is not restricted to central-northern Argentina and Uruguay, but has been hidden because workers simply ignored this type of hosts in most ecological tick studies in others localities. This is especially noteworthy for Microcavia because it is considered that lack or poor tick searching is the explanation for the scarcity of findings (only one record) of hard ticks on rodents of this genus, in spite of the ample distribution that the members of Microcavia have in southern Neotropical Region. Additional ecological tick studies are needed to confirm this hypothesis.
Amblyomma parvum, A. tigrinum and A. triste are species recognized as parasites of man and domestic mammals; therefore the feeding of sub-adults ticks on Caviinae should have sanitary consequences. These rodents may constitute the route for wild tick-borne pathogens to reach man and domestic animals, a situation that needs investigations.

ACKNOWLEDGEMENTS

We are very grateful to Darci M. Barros-Battesti (Instituto Butantan, São Paulo, Brazil) for providing the data on the specimens deposited in the Acari Collection from Instituto Butantan. Support for the authors was provided by the Instituto Nacional de Teconlogía Agropecuaria, the Asociación Cooperadora of EEA-INTA Rafaela and Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.

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