There's still a lot of ongoing debate whether the
correct taxonomical nomenclature should be
Monogenea or Monogenoidea. In this current note it
will be addressed as Monogenea, since it's the most
traditional (Wheeler & Chisholm, 1995), and
therefore most known nomenclature. But the
authors would like to point that we support the use
of Monogenoidea for its phylogenetic approach.
Monogenea is the denomination of a class of
parasitic flukes belonging to the Platyhelminthes
phylum. They are divided over more than 50
families with thousands of described species. Some
estimation presumes that there is at least one species
of Monogenea for every species of fish. Most
species are highly host specific, having no more
than one host, but some are reported to be generalist
(Eiras, 1994).
They are found both in marine and freshwater
fishes, where they can act as ectoparasites on skin
and gills, feeding on mucus, skin cells and blood, or
as endoparasites in stomach. They attach
themselves to hosts using a structure called haptor,
located in the posterior region, and feed using an
anterior oral sucker.
These parasitic flatworms lack respiratory, skeletal
and circulatory systems but have a complex
reproductive system. They are hermaphroditic,
mostly with a direct life cycle, being either
oviparous or viviparous. Viviparous Monogenea
can host several generations inside them, awarding
them the nickname of “russian dolls” (Bakke et al.,
2007). Because of their life cycle, they proliferate
very quickly in environments with high host
densities, such as fish tanks or ponds (Takemoto et
al., 2004).
They are important fish disease agents, being
responsible for many mass mortalities events
around the world, especially in the aquaculture
industry, but sometimes even in natural
environment, such as the mass mortality of the
anchovy Engraulis japonica Temminck &
Schlegel, 1846 in the Sea of Iyo, which killed over
87,000 fish (Yamamoto et al., 1984).
Histology studies show that on the gills, they induce
an excessive mucus production, hyperplasia and
can lead to fusion of gills lamellae, causing
mortality, especially under poor environmental
conditions such as low oxygen content (Molnár,
1994; Pavanelli et al., 2002). In Brazil, Martins &
Romero (1996) have reported that in severe
infestations caused hyperplasia in the primary
lamellae, necrosis, edema, respiratory epithelium
displacement, ruptured pillar cells and
telangiectasis.
Nile tilapia is one of the most cultured fishes in the
world with more than 2 million tonnes produced
worldwide (FAO, 2009). In Brazil, it's the most
produced freshwater fish, reaching over 70
thousand tonnes per year, which corresponds to
26% of the national aquaculture production
(Boscardin, 2008).
Monogenea are among the major parasites on Nile
tilapia, even though in Brazil there are few cases of
mass mortalities caused by high Monogenea
infestations, they are responsible for significant
economical losses, since in most cases the host
shows a decrease in the respiratory and growth rate
(Martins & Romero, 1996).
The following Monogenea species have currently
been described in cultured Nile tilapia in Brazil:
ectoparasitic Cichlidogyrus sclerosus
Papaloapanerna y Thurston, 1969, Cichlidogyrus
halli Price & Kirk, 1967, Cichlidogyrus thurstonae
Ergens, 1981, Scutogyrus longicornis Paperna &
Neotrop. Helminthol., 3(2), 2009
2009 Asociación Peruana de Helmintología e Invertebrados Afines (APHIA)
EDITORIAL
ON THE IMPORTANCE OF MONOGENEAN HELMINTHES IN
BRAZILIAN CULTURED NILE TILAPIA
1
Eduardo L.T. Gonçalves.; Gabriela T. Jerônimo & Mauricio Laterça-Martins
Suggested citation: Gonçalves, E.L.T.; Jerônimo, G.T.; Martins, M.L. 2009. On the importance of monogenean
helminthes in brazilian cultured nile tilapia. Neotropical Helminthology. vol. 3, nº 2, pp. 53-56.
LA IMPORTANCIA DE LOS HELMINTOS MONOGENEOS EN
EL CULTIVO DE TILAPIA DEL NILO EN BRASIL
53
Aquaculture Department, Federal University of Santa Catalina, Florianapolis, SC, Brasil.
1
54
Monogenean in Tilapia
Thurston, 1969 (Monogenoidea: Dactylogyridae)
and endoparasitic Enterogyrus cichlidarum
P a p e r n a , 1 9 6 3 ( M o n o g e n o i d e a :
Ancyrocephalidae). (Jerônimo, 2009)
In Brazil, the major groups that work with
Monogenea helminthes are located in Rio Grande
do Sul, Santa Catarina, Paraná, São Paulo, Rio de
Janeiro, Mato Grosso do Sul, Piauí, Amazônia,
Pará, Amapá. However, not every group work with
quantification and fewer are the ones who work
with cultured Nile tilapia, which restricts the
available data over Monogenean helminthes in
cultured Nile tilapia to three main states: São Paulo,
Paraná and Santa Catarina.
A problem that hinders the development of
quantification studies and makes it harder for data
comparison is the lack of standardization over the
quantification methods and parameters for
Monogenea. Therefore, some efforts should be
made towards a national standard procedure for
quantification parameters and methods.
The following graphics (Figure 1-2) represents the
data over prevalence rates and mean infestation
intensities for Monogenea gathered from 20 papers
that studied the parasitic fauna in cultured Nile
tilapia.
Figure 1. Boxplot graphic for prevalence rate of Monogenea in cultured Nile tilapia, based on a review over 20
papers, Brazil, 2009.
Figure 2. Mean intensity of Monogenea in cultured Nile tilapia, based on a review over 20 papers, Brazil, 2009.
Gonçalves et al.
Mean Intensity
Boxplot by Group
Variable: Prevalence Rate (%)
100%
80%
60%
40%
20%
0%
São Paulo Paraná Santa Catarina
State
Median
25%-75%
Min-Max
Prevalence Rate (%)
Correspondence to author/Autor para
correspondencia:
Maurício Laterça Martins.
Aquaculture Department, Federal University of
Santa Catarina (UFSC), Rod. Admar Gonzaga
1346, 88040-900, Florianopolis, SC, Brazil.
E-mail: mlaterca@cca.ufsc.br
(Monogenea) infection of varying severity.
Diseases of Aquatic Organisms, vol.20, pp.153-
157. Doenças
de peixes: profilaxia, diagnóstico e tratamento.
Maringá: Universidade Estadual de Maringá.
Parasitos de peixes de aguas
continentais. In: Ranzani-Paiva, MJT, Takemoto, R
& Lizama, MAP. Sanidade de Organismos
Aquáticos. São Paulo: Varela, pp. 179-197.
Monogenea versus
Monogenoidea: the case for stability in
nomenclature. Systematic Parasitology, vol. 30,
pp. 159-164. Mass
mortality of the Japanese anchovy (Engraulis
japonica) caused by a gill monogenean
Pseudanthocotyloides sp. (Mazocraeidae) in the
Sea of Iyo ('Iyo-Nada'), Ehime Prefecture. Fish
Pathology, vol. 9, pp. 119–123.
Pavanelli, GC, Eiras, JC & Takemoto, RM. 2002.
Takemoto, RM, Lizama, MAP, Ghidelli, GM, Pavanelli,
GC. 2004.
Wheeler, TA & Chisholm, LA. 1995.
Yamamoto, K, Takagi, S & Matsuoka, M. 1984.
BIBLIOGRAPHIC REFERENCES
Bakke, TA, Cable, J & Harris, PD. 2007.
Boscardin, NR. 2008.
Eiras, JC. 1994.
FAO. 2005-2009.
Jerônimo, GT. 2009.
Martins, ML & Romero, NG. 1996.
Molnár, K. 1994.
The biology of
Gyrodactylid Monogeneans: the “Russian-doll
killers”. Advances in Parasitology, vol. 64, pp.
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Monogenean in Tilapia Gonçalves et al.
