Forma de citar: Pinhão, R.; Wunderlich, A. C.; Anjos, L. A.; Silva, R. J. 2009. Helminths of toad Rhinella icterica (Bufonidae),

from the municipality of Botucatu, São Paulo State, Brazil. Neotropical Helninthology, vol. 3, nº1, pp. 35-40..

Resumen

Palabras clave: Acanthocephala – Amphibia - Fauna helmíntica -

Índice de discrepancia –Nematoda - Rhinella icterica.

Quince ejemplares del sapo bufonido Rhinella icterica (Spix, 1824), 7 machos y 8 hembras, colectados en el

municipio de Botucatu, Estado de São Paulo, Brasil, desde marzo del 2002 hasta enero del 2003, fueron

analizados en busca de helmintos parásitos. Todos los sapos estaban infectadas con al menos un parásito

(prevalencia global = 100%). Cinco especies de helmintos fueron encontradas, entre ellas cuatro especies de

nematodos, Rhabdias fuelleborni Travassos, 1926, Oswaldocruzia subauricularis (Rudolphi, 1819), gen. sp.

no identificada Cosmocercidae Travassos, 1925 y larvas de Physaloptera Rudolphi, 1819, y una especie

acantocéfalo, Acanthocephalus saopaulensis Smales, 2007. Rhabdias fuelleborni y A. saopaulensis fueron

las especies más abundantes. A excepción de las larvas de Physalopteridae, todos los helmintos presentaron

una alta prevalencia (> 70%). Todas las especies de helmintos presentaron una tendencia hacia un patrón más

agregado de distribución en los hospederos muestreados.

Key words: Acanthocephala - Amphibian - Discrepancy index -

Helminth fauna - Nematoda - Rhinella icterica.

Abstract

Fifteen specimens of bufonid toad Rhinella icterica (Spix, 1824), 7 males and 8 females, collected in the

municipality of Botucatu, São Paulo State, Brazil, from March 2002 to January 2003, were examined for

helminth parasites. All toads were infected with at least one parasite species (overall prevalence = 100%).

Five helminth species were found, including four nematode species, Rhabdias fuelleborni Travassos, 1926,

Oswaldocruzia subauricularis (Rudolphi, 1819), gen. sp. no identified Cosmocercidae Travassos, 1925 and

larvae of Physaloptera Rudolphi, 1819, and one acanthocephalan species, Acanthocephalus saopaulensis

Smales, 2007. Rhabdias fuelleborni and A. saopaulensis were the most abundant species. Except for

Physalopteridae larvae, all helminths occur in high prevalence (> 70%). All helminth species presented a

distribution toward to more aggregated pattern in these host samples.

Neotrop. Helminthol., 3(1), 2009

2009 Asociación Peruana de Helmintología e Invertebrados Afines (APHIA)

HELMINTHS OF TOAD RHINELLA ICTERICA (BUFONIDAE),

FROM THE MUNICIPALITY OF BOTUCATU, SÃO PAULO STATE, BRAZIL

HELMINTOS DEL SAPO RHINELLA ICTERICA (BUFONIDAE),

DE LA MUNICIPALIDAD DE BOTUCATU, ESTADO DE SÃO PAULO, BRAZIL

1 1 1 1

Rebeca Pinhão , Alison Carlos Wunderlich , Luciano Alves dos Anjos & Reinaldo José da Silva. *

1 UNESP - Univ de Estadual Paulista, Campus de Botucatu, Instituto de Biociências, Departamento de Parasitologia, Botucatu,

São Paulo, Brazil.

INTRODUCTION

The Neotropical region harbors the highest

amphibian biodiversity (Frost, 1985; Izecksohn &

Carvalho-Silva, 2001) and Brazil has a great

number of amphibian species of the world (IUCN,

2009; SBH, 2009). The knowledge of the helminth

amphibian parasites is lower and the majority of

studies dealing with their parasites are taxonomic

descriptions and only few ones have been focused

parasite populations and community structure

(Goldberg et al., 1995; Linzey et al., 1998; Puga &

Torres, 1999; Boquimpani-Freitas et al., 2001;

Bursey et al., 2001; Goldberg & Bursey, 2003;

Luque et al., 2005; Holmes et al., 2008; Campião et

al., 2009).

The Cururu toad, Rhinella icterica (Spix, 1824), is

largely distributed in the South American, inhabits

forest regions, open vegetal formations and

eventuality urban ambient (Izechsohn & Carvalho-

Silva, 2001; Silvano et al., 2004). Despite of little

knowledge on amphibian parasites, the helminth

fauna of this species have been well studied (Kloss,

1971; Faria, 1978; Rodrigues et al., 1978, 1982;

Vicente et al., 1990; Martins, 2004, Luque et al.,

2005), however, only Luque et al. (2005) focused

on the ecological data of helminths of R. icterica

from Rio de Janeiro State, Brazil.

The aim of this study was to evaluate the helminth

fauna of the Cururu toad R. icterica in the

municipality of Botucatu, São Paulo State, Brazil.

A total of 15 animals comprising 7 males and 8

females were collected from March 2002 to

January 2003 in the municipality of Botucatu, São

Paulo State, Brazil. The toads were captured in a

ruderal field around ponds and streams. The toads

were euthanatized with sodium thiopental solution

and after examined for helminth parasites. In the

laboratory, toads were necropsied and body cavity,

lungs and the gastrointestinal tract were surveyed

for endoparasites. The helminths were fixed in

alcohol-formaldehyde-acetic acid (AFA) and

stored in 70% ethanol.

For identification, acanthocephalans were stained

with carmine and cleared with eugenol. Nematodes

were cleared with lactophenol. Mean intensity of

infection, mean abundance and prevalence was

calculated according to Bush et al. (1997).

The discrepancy index (D) was calculated as

suggested by Poulin (1993). The index has a

minimum value of zero (D = 0), when all hosts

harbor the same number of parasites. When all

parasites are found in a single host, aggregation is

maximum (D = 1). This index was calculated with

software Quantitative Parasitology 3.0 (Rózsa et

al., 2000). Voucher helminth specimens were

deposited in the Coleção Helmintológica do

Instituto de Biociências de Botucatu (CHIBB) at

the Universidade Estadual Paulista, São Paulo

State, Brazil.

All toads were infected with at least one parasite

species (overall prevalence = 100%). Five helminth

species were found, including four nematode

species, Rhabdias fuelleborni Travassos, 1926,

Oswaldocruzia subauricularis (Rudolphi, 1819),

Cosmocercidae gen. sp. no identified Travassos,

1925 and larvae of Physaloptera Rudolphi, 1819,

a n d o n e a ca n th o c e p h al a n s p ec i es ,

Acanthocephalus saopaulensis Smales, 2007

(Table 1).

Regarding the infection sites, lungs harbored only

R. fuelleborni, at stomachs only larvae of

Physaloptera were found; on the small and large

intestines were found A. saopaulensis and O.

subauricularis, and further the unidentified

Cosmocercidae species were found at large

intestine (Table 1). Except for Physaloptera larvae,

all helminths occurred in high prevalence (> 70%).

Rhabdias fuelleborni and A. saopaulensis were the

most abundant species. With relation to intensity of

infection, A. saopaulensis and R. fuelleborni

presented the higher mean intensities of infection

(Table 1).

All helminths species presented a distribution trend

to aggregate in this host sample (Table I). The

majority of infected amphibian harbored four

helminth species (47%, n = 7), with a smaller

percentage harboring three (33%, n = 5) or two

species (20%, n = 3) (Figure 1).

MATERIALS AND METHODS

RESULTS

Helminths of Rhinella

Pinhão et al.

Nematodes are the main helminth parasites found

in the toad R. icterica (Luque et al., 2005), with few

record of acanthocephalan infecting this anuran

species (Smales, 2007). However, in this study A.

saopaulensis was the more prevalent (86.7%) and

abundant (723 specimens) parasite species.

Acanthocephalus saopaulensis was recently

described by Smales (2007) as new species of toad

R. icterica, with low prevalence (33.3 %), mean

intensity (22), and abundance (7.3). The present

study found higher infection pattern than the data

presented by Smales (2007) (Table 2), suggesting a

different composition in the helminth parasite

community associated with geographical variation.

Also, the helminth richness found infecting R.

icterica in São Paulo State was smaller than from

Rio de Janeiro State (Luque et al., 2005),

reinforcing the environment component in the

establishment of the helminth fauna of this anuran

species.

Rhabdias fuelleborni and species of the genus

Cosmocerca Diesing, 1861 infect several anurans

species and occurs in many countries in South

America (Baker & Vaucher, 1984; González &

Hamann, 2004; Goldberg et al., 2007). Rhabdias

fuelleborni was registered in host population from

R. icterica (Vicente et al., 1990; Luque et al.,

2005), R. marina and R. schneideri (Vicente et al.,

1990). All infection parameters, such as

prevalence, mean intensity of infection and mean

abundance, were higher on toads from Botucatu

municipality (São Paulo State) in contrast to toads

from Miguel Pereira municipality (Rio de Janeiro

State) which has available data on literature (Luque

et al., 2005).

Rhabdias fuelleborni has been reported for R.

marina, with high prevalence, intensity and

abundance means (Ragoo & Omah-Maharaj,

2003). Regarding the genus Cosmocerca, Vicente

et al. (1990) reported several helminth parasite

species for R. icterica.

Oswaldocruzia subauricularis were recorded

harboring intestine of two populations of R.

icterica, one from Curitiba municipality (Paraná

State) (Vicente et al., 1990) and other from Miguel

Pereira municipality (Luque et al., 2005). In

comparison with last population, all infection

parameters were higher on toads from Botucatu

municipality (Table II).

According Aho (1990), the higher richness

helminth fauna in amphibians host are related to

time that hosts spend in water during larval stages

and breeding season. In this period the anurans are

exposed to acanthocephalans and other helminths

that are typically transmitted through the ingestion

of aquatic invertebrates. Further, during terrestrial

life-cycle hosts are exposed to transcutaneous

penetration by nematode larvae (e.g. Rhabdias spp.

and some Cosmocercidae) and ingestion of eggs of

nematodes (such as Trichostrongylidae Leiper,

1912 and Cosmocercidae) (Aho, 1990). Moreover,

this toad species presents a wide feeding spectrum

that include 27 food items (Sabagh & Carvalho-e-

Silva, 2008), increasing the possibility of infection

by a large number of species of parasites.

The higher prevalence, mean intensity of infection

and abundance, mainly for A. saopaulensis, found

in this R. icterica population could be related to

differences in local composition of helminth

species (component community, sensu Bush et al.,

1997) or host ecological characteristics such as

aggregation of the host population and differential

consumption of dietary items. However, additional

studies on other R. icterica population in a wide

geographical distribution could improve the

knowledge of this host-parasites relationship.

A high infection rate by cosmocercid nematodes

(prevalence = 80%; mean intensity of infection =

16 ± 5.5, range 1-68) was observed in the studied

sample, however, the species was not identified

because only females were found in all anuran

hosts. The absence of males and the high number of

eggs containing larvae may suggest a

parthenogenetic reproduction mechanism in this

helminth population, similar to other nematodes

such as Strongyloides spp. and Rhabdias spp.

(Anderson, 2000). We have no information on the

occurrence of parthenogenesis in Cosmocercidae

and so future studies will be conducted to better

understanding this curious case.

DISCUSSION

Neotrop. Helminthol., 3(1), 2009

Helminths of Rhinella

Pinhão et al.

Helminth

Prevalence

(%)

MA ± SE

MII ± SE

(range)

Site of

infection

Nematoda

Cosmocercidae

CHIBB 289, 293, 297, 301,

303, 309, 314, 321, 326, 330,

334, 344, 350

12.8 ±

4.7

(0-68)

16 ±

5.5

(1-68)

0.595

Large

intestine

Rhabdias fuelleborni

CHIBB 286, 290, 294, 298,

310, 315, 318, 322, 327, 331,

335, 338, 341

30.3 ± 10.1

(0-105)

37.8 ± 11.6

(3-105)

0.596

Lung

Oswaldocruzia subauricularis

CHIBB 288, 292, 296, 300,

304, 305, 306, 313, 324, 325,

333, 336, 337, 339, 343, 345,

348

73.3

5.6 ± 1.4

(0-20)

7.6 ± 1.5

(2-20)

0.476

Small and

large

intestine

Physalopteridae larvae

CHIBB 332

6.7

0.4

stomach

Acanthocephala

Acanthocephalus saopaulensis

CHIBB 287, 291, 295, 299,

302, 307, 308, 311, 312, 316,

317, 319, 320, 323, 328, 329,

340, 342, 346, 347, 349

86.7

48,2 ± 12,8

55,6 ± 13,6

(1-190)

0.471

Small and

large

intestine

Table 1. Prevalence, mean abundance (± standard error), mean intensity (± standard error), discrepancy index (D), and site of

infection of helminths from Rhinella icterica (n = 15) from Botucatu, São Paulo State, Brazil. MA - mean abundance. MII - mean

intensity of infection. CHIBB - Coleção Helmintológica do Instituto de Biociências de Botucatu.

PARASITE Prevalence

(%) Nº

sampled Range Mean Intensity

± SE Mean Abundance

± SE Infection

Site Reference

33.3

86.7

55.6 ± 13.6

7.3

48.2 ± 12.8 I

SI, LI

Smales (2007)

present study

Acanthocephalus

saopaulensis

1-190

12.5

73.3 32

1 - 9

4.5 ± 0.7

7.6 ± 1.5

0.5 ± 0,3

5.6 ± 1.4 SI

SI, LI Luque et al. (2005)

present study

Oswaldocruzia

subauricularis

2 - 20

53.1

80.0 32

15 1 - 31

8 ± 1.6

37.8 ± 11.6

4.2 ± 1.3

30.3 ± 10.1 LLuque et al. (2005)

present study

Rhabdias

fuelleborni

3 - 105 L

Table 2. Comparison between prevalence, mean intensity (± standard error), mean abundance (± standard error) and infection

site of three population of toad Rhinella icterica. I = intestine; SI = small intestine; LI = large intestine; L = lung.

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Figure 1. Percentage of Rhinella icterica (n = 15) infecting

with two, three or four helminth species in the municipality of

Botucatu, São Paulo State, Brazil.

2 3 4

Infected hosts (%)

Richness of helminth species

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*Correspondence to author/Autor para correspondencia:

Reinaldo José da Silva,

Departamento de Parasitologia, Instituto de Biociências,

Universidade Estadual Paulista, Botucatu, São Paulo, Brazil.

Correo electrónico/E-mail: reinaldo@ibb.unesp.br

Neotrop. Helminthol., 3(1), 2009