Ticks (Acari: Ixodidae) from yellow armadillo, Euphractus sexcinctus (Cingulata: Dasypodidae), in Brazil's Pantanal wetlands

SCIENTIFIC NOTE

^IUniv de Brasília, Instituto de Ciências Biológicas, Depto de Zoologia, 70910-900, Brasília, DF, Brasil; [e-mail]; [e-mail]

^IIInstituto de Pesquisas Veterinárias Desidério Finamor, FEPAGRO, Lab de Parasitologia, 92990-000, Eldorado do Sul, RS, Brasil; [e-mail]; [e-mail]

^IIIEmbrapa Pantanal, Lab de Fauna Silvestre, 79320-900, Corumbá, MS, Brasil; [e-mail]

ABSTRACT

Tick species parasitizing yellow armadillo, Euphractus sexcinctus, were recorded from October 2006 to October 2007 in Pantanal. A total of 89 ticks were collected from 23 yellow armadillos. Most ticks (n = 50) were identified as Amblyomma cajennense (Fabricius) (32 males and 18 females). The only other species found was Amblyomma parvum (Aragão) (three females and two males). The remaining ticks were immatures of Amblyomma (29 nymphs and five larvae). The prevalence of A. cajennense was 55%, the mean intensity was 2.7 ± 0.5 (SE) (n = 17) and the mean abundance was 1.5 ± 0.4 (n = 31).

Key words:Amblyomma cajennense, Amblyomma parvum, ectoparasite

Ticks are obligatory hematophagous ectoparasites of vertebrates acting as vectors of pathogens to animals, including humans. Moreover, they can cause local irritations and inflammatory processes, anemia resulting from high infestations, predisposition to myiases, secondary bacterial infections, and skin alterations (Jongejan & Uilenberg 2004). The majority of studies have focused on ticks of domestic animals. However, it is important to know more about parasitic ticks of wild animals, because many of these species can be vectors of pathogens causing emergent zoonoses.

Studies conducted in Brazilian Pantanal (Campos Pereira et al 2000) and in the Cerrado biome report tick species associated with armadillos (Botelho et al 1989, Bechara et al 2002). In most of these studies, the species of Amblyomma Koch, were dominant. Amblyomma is the richest tick genus (33 species) in Brazil (Aragão & Fonseca 1961). The purpose of the present study was to determine the species of ticks associated to the yellow armadillo, Euphractus sexcinctus, in the Pantanal wetlands.

The study was conducted monthly from October 2006 to October 2007 with the exception of January, June and July, at the Embrapa Pantanal experimental station known as the Nhumirim Ranch (18º59'S; 56º39'W), located at the municipality of Corumbá, Mato Grosso do Sul, Brazil. The region comprises a mosaic of permanent and temporary ponds, forest patches, savanna, scrub savanna and seasonally flooded grasslands on sandy soils. Annual precipitation is 1,182 mm, and the average annual temperature is 25.5ºC (Soriano et al 1997).

Yellow armadillos were caught by hand, placed in a plastic carrier box with adequate ventilation, and taken to the laboratory of the ranch. Animals were anesthetized (4 mg/kg of tiletamine and zolazepam - Zoletil^® 50, Virbac do Brasil, Jurubatuba, São Paulo), and ticks and blood samples were taken for further studies. Ticks were manually removed from the armadillos and placed in 70% ethanol. The armadillos were released at the same day in the same site of capture. Tick species were identified with the following keys: Aragão & Fonseca (1961), Guimarães et al (2001) and Onofrio et al (2006). Nymphs and larvae of Amblyomma were not identified to species because there was not any available key to immature Amblyomma of the Neotropical region until the moment of ticks analysis. The ticks were deposited in the collection of Instituto de Pesquisas Veterinárias Desidério Finamor, Rio Grande do Sul, Brazil.

The prevalence, mean intensity and mean abundance were calculated according to the procedures described by Margolis et al (1982) and Bush et al (1997). Prevalence = the number of hosts infested with one or more individuals of a parasite species, divided by the number of hosts examined for that parasite species; mean intensity = the total number of parasites of a species found in a sample divided by the number of hosts infested with that parasite; and mean abundance = the total number of individuals of a parasite species in a sample of a host species divided by the total number of hosts of that species examined, including both infested and not infested hosts. The recaptures of yellow armadillos were not considered in the calculation of these rates.

Of 31 yellow armadillos (16 males and 15 females) captured in the Pantanal, 23 (12 males and 11 females) contained ticks. There was no significant difference between the number of parasitized yellow armadillos of both sexes (χ² = 0.002; P = 0.96). The prevalence of infestation by ticks among the yellow armadillos was 74%. One individual was recaptured twice in the interval of at least two months between captures and another individual was recaptured once. A total of 26 collections of ticks from yellow armadillos were carried out. The parasited individuals showed low intensity of infestation: the two animals with the largest number of ticks had 11 ticks each. Eighty-nine ticks were collected during this study. Most of them were found in the ventral region of the armadillos; a single specimen was found on the skin between the moveable bands, on the dorsum of the animal. Of this total, 56% were identified as Amblyomma cajennense (Fabricius) and 6% as Amblyomma parvum (Aragão). The remaining ticks were represented by Amblyomma immatures: nymphs (32%) and larvae (6%) (Table 1). Most armadillos carried a single tick species, except for four individuals infested by A. cajennense and A. parvum simultaneously.

The prevalence of A. cajennense was 55%, the mean intensity was 2.7 ± 0.5 (SE) (n = 17) and the mean abundance was 1.5 ± 0.4 (n = 31). Forty-seven ticks of this species were collected in 17 of 31 armadillos examined only once (not recaptured). Four A. parvum were found on four different hosts not recaptured. Prevalence was 13%, mean intensity was 1 ± 0 (n = 4), and mean abundance was 0.1 ± 0.1 (n = 31). Prevalence of Amblyomma larvae and nymphs was 45%, mean intensity was 2.3 ± 0.7 (n = 14), and mean abundance was 1 ± 0.4 (n = 31). Fifty-five of the ticks collected were adults, 29 were nymphs and five were larvae. The predominant species, A. cajennense, was collected throughout the year, with highest mean abundance in October (4 ± 1.8; n = 3), November (3 ± 0; n = 2), March (4.3 ± 2.3; n = 3) and April (2.6 ± 0.9; n = 5). Amblyomma parvum was collected only in April, May and August. Highest mean abundance of nymphs of Amblyomma sp. was observed in August (3.7 ± 2.5; n = 4). The total number of collected ticks did not correlate with the number of yellow armadillos captured per month (r² = 0.37; P = 0.06). Campos Pereira et al (2000) reported that Amblyomma species were abundant in the Pantanal, finding a predominance of nymphs in August and September.

Although other species of Amblyomma have been reported associated to yellow armadillos (Botelho et al 1989, Guglielmone & Viñabal 1994, Campos Pereira et al 2000, Bechara et al 2002, Robins et al 2003), our data indicate A. cajennense as the predominant tick of yellow armadillos in Pantanal.

Acknowledgments

We are grateful to Valeria C. Onofrio for confirming the identification of the tick species; Maurício B. Sampaio for reviewing the manuscript; CAPES and CNPq for awarding doctoral grants to Ísis M. Medri; CNPq for the productivity fellowships awarded to Jader Marinho-Filho and Guilherme Mourão; Embrapa Pantanal for the logistic support; PELD/CNPq (process 520056/98-1) for financial support; IDEA WILD for donating equipment; and IBAMA for permission to capture yellow armadillos in the studied area (permit number 02038.000114/06-90).

Received 29/IX/08.

Accepted 30/III/10.

Edited by Gilberto J de Moraes - ESALQ/USP

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Ticks (Acari: Ixodidae) from yellow armadillo, Euphractus sexcinctus (Cingulata: Dasypodidae), in Brazil's Pantanal wetlands

Ísis M Medri^I; João R Martins^II; Rovaina L Doyle^II; Guilherme Mourão^III; Jader Marinho-Filho^I

Publication Dates

• Publication in this collection
  19 Nov 2010
• Date of issue
  Oct 2010

History

• Accepted
  30 Mar 2010
• Received
  29 Sept 2008