Austrodiplostomum compactum metacercariae (Digenea: Diplostomidae) in Schizodon intermedius (Characiformes: Anostomidae) from Jurumirim reservoir, Brazil

Abstract

This study reports the occurrence of Austrodiplostomum compactum metacercariae in the freshwater fish Schizodon intermedius (ximborê/piava) from a Neotropical reservoir in the Paranapanema River, state of São Paulo, Brazil. From a total of 75 fish collected, we found 38 infected with A. compactum metacercariae (prevalence = 50.67%) in the eyes. The mean intensity of infection and mean abundance were 9.05 ± 4.26 (1-155) and 4.59 ± 2.20 (0-155), respectively. Poulin's Discrepancy Index was 0.87 and four specimens presented more than 10 metacercariae in their eyes. No correlation was observed between parasite abundance and standard length, total weight and condition factor (p>0.05). These metacercariae are reported for the first time in S. intermedius.Keywords: Freshwater fish, eyefluke, ximborê, Paranapanema River, Paraná River basin. ResumoEste estudo reporta a ocorrência de metacercárias de Austrodiplostomum compactum na espécie de peixe de água doce Schizodon intermedius (ximborê/piava), oriunda de um reservatório Neotropical no rio Paranapanema, Estado de São Paulo, Brasil. Um total de 75 peixes foram coletados, sendo que 38 estavam infectados com metacercárias de A. compactum (prevalência = 50,67%) nos olhos. A intensidade média de infecção e abundância média foram 9,05 ± 4,26 (1-155) e 4,59 ± 2,20 (0-155), respectivamente. O Índice de Discrepância de Poulin foi de 0,87, e quatro exemplares apresentaram mais do que 10 metacercárias em seus olhos. Não foram observadas correlação entre abundância média e comprimento padrão, peso total e fator de condição (p>0,05). Esse é o primeiro registro dessa espécie de metacercária para S. intermedius.Palavras-chave: Peixe de água doce, trematódeo parasita de olho, ximborê, rio Paranapanema, bacia do rio Paraná. (KARVONEN et al., 2006;VIOLANTE-GONZÁLEZ et al., 2009). Adults of diplostomids release their eggs into water via the feces of infected piscivorous birds, and hatching of free-swimming larva (miracidia) can occur up to 22 days later, depending on the water temperature (GROBBELAAR et al., 2014). In Brazil, miracidium actively infect aquatic snails of the genus Biomphalaria Preston, 1910 (PINTO & MELO, 2013, and polyembriony occurs in the digestive gland and liver of snails (CROWDEN & BROOM, 1980;HOFFMAN & HUNDLEY, 1957). Infected snails release cercariae, which actively infect fish (second intermediate host), preferentially through their gills and mouth (HAAS et al., 2007), although penetration may also occur through their fins and body surface (GROBBELAAR et al., 2014).In fish, the parasites develop to the metacercariae, which generally parasitize the eyes ) and brain (GROBBELAAR et al., 2014). The adult/reproductive form of this parasite species is found in the digestive system of piscivorous birds, when these birds feed on infected fish. Neotropical cormorants, Phalacrocorax brasilianus (Gmelin, 1789), which are a widespread generalist species, are considered to be the definitive host of this diplostomid in Brazil (MONTEIRO et al., 2011).According to Grob...

Occurrence of metacercariae of Austrodiplostomum compactum (Lutz, 1928) (Trematoda, Diplostomidae) in Pimelodus platicirris in the Ilha Solteira Reservoir, São Paulo, Brazil

“…These data corroborate the observations of Ramos et al (2013), Ramos et al (2016) and Barrett et al (2019) which reported that fish farm contributed with resources, in the form of organic matter, to the aquatic environment, attracting the local biota and altering the abundance of intermediate hosts (gastropods and fish). These, in turn, may attract the definitive hosts (piscivorous birds), resulting in an increase in the dissemination/availability of infective forms of A. compactum in areas near to fish farms.…”

Ithyoclinostomum dimorphum Diesing, 1850 (Digenea, Clinostomidae) in Hoplias malabaricus (Erythrinidae) with the fi rst report of infection of the eyes

“…Due to the low parasitism of I. dimorphum , which occupied almost all of the eyeball, no damage to the prey capturing performance by the host was observed, and the body characteristics of the examined host population were not affected. However, when migrating to the host fish eyes other metacercariae may cause exophthalmos, retinal detachment, cataracts and blindness or even death (Zago et al ., 2013; Belei et al ., 2013; Ramos et al ., 2016) when at high levels of abundance.…”

“…No difference was observed in the Kn of H. malabaricus parasitized by I. dimorphum and non-parasitized fish due to the low parasite infection in the intestine, eyes and muscles. Similarly, other studies have also shown that low parasitism by the metacercariae of digeneas did not affect the host condition factor (Paes et al ., 2010; Ramos et al ., 2016). On the other hand, an increased abundance of metacercariae of Sphincterodiplostomum musculosum in Steindachnerina insculpta caused a reduction in the condition factor of the hosts (Zago et al ., 2013), because digenea larvae can be highly pathogenic.…”

Metacercariae of Austrodiplostomum compactum (Trematoda, Diplostomidae) in non-native fish species in Brazil: a possible explanation for the high rate of parasitic infection

“…Although, cercariae emerge from the tegument of gastropods such as: Biomphalaria straminea (Dunker, 1848), Biomphalaria glabrata (Say, 1818) (Pinto & Melo 2013), Biomphalaria prona (Martens, 1873) (Ostrowski de Núñez 1982), Biomphalaria obstructa (Morelet, 1849) (Rosser et al 2016) and larval forms (metacercariae) can inhabit the eyes of several species of freshwater fishes (Yamada et al 2008, Ramos et al 2013). According to Ramos et al (2013Ramos et al ( , 2016 and Campos et al (in press), metacercariae of A. compactum have been reported in 38 Brazilian fish species belonging to 13 families of four orders, highlighting the high infection rates in Plagioscion squamosissimus (Heckel, 1840).…”