This study is the first investigation on seasonal dynamics of parasites component community of the Aequidens tetramerus from an Amazon River tributary, in Northern Brazil. A total of 239,2407 parasites were recovered from 92 hosts examined from February to October 2011. Such parasites included Ichthyophthirius multifiliis, Tripartiella tetramerii and Trichodina nobilis (Protozoa), Dolops longicauda (Argulidae), Gussevia alioides, Gussevia disparoides (Monogenoidea), Digenea metacercarie, Pseudoproleptus larvae, Anisakidae larvae (Nematoda), Proteocephalidea plerocercoid (Eucestoda) and Gorytocephalus spectabilis (Acanthocephala). Ciliates were the most dominant and abundant taxon, while cestodes were the least prevalent. The parasites showed seasonal variation in their infection dynamics associated with environmental changes during the Amazonian drainage season, except the infection with I. multifiliis. The parasites community in A. tetramerus was also characterized by higher diversity, species richness and uniformity during the drainage season when compared to Amazon flood season. With the exception of T. tetramerii, these parasite species are new records for A. tetramerus.

This study investigated the in vivo and in vitro antiparasitic effects of the essential oil of Lippia alba and the bloodrelated and histopathological alterations that it causes in Colossoma macropomum. In the in vitro trial, the anthelminthic effects of 160, 320, 640, 1280 and 2560 mg/L of the essential oil were tested against monogenoideans (Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri) of the gills of this fish, which are its natural parasites. The concentrations of 1280 mg/L and 2560 mg/L showed 100% efficacy after 20 min of exposure to the essential oil, while at lower concentrations this efficacy against the gill monogenoideans only occurred after 2-3 h of in vitro exposure. However, in the controls, mortality of all of these monogenoideans only occurred after 9 h. A total of 240 fry were distributed into four treatments (20 fish per repetition) and three repetitions were used in the in vivo trial for baths with 100 and 150 mg/L of the essential oil of L. alba, for 30 min. The efficacy in this trial against Ichthyophthirius multifiliis in fish exposed to 100 and 150 mg/L of the essential oil was 40.7% and 50.3%, respectively. However, for monogenoideans, there was efficacy of 14.0% only in the fish exposed to 100 mg/L of the essential oil used. Moreover, the fish exposed to these concentrations of the essential oil presented increased plasma glucose levels, thus denoting signs of stress. Severe lesions such as hyperplasia, fusion of the lamellar epithelium, capillary dilatation, epithelial detachment, lamellar aneurysm, epithelial rupture with hemorrhage, congestion, edema, necrosis, mucous cell proliferation, chloride cells and lamellar hypertrophy were observed in the gills of the fish exposed to 100 and 150 mg/L of the essential oil of L. alba. Alterations to total protein levels, hemoglobin, hematocrit, red blood cell number, thrombocytes number, white blood cell number, lymphocytes, eosinophils and blood neutrophil number was also observed in these fish. The essential oil of L. alba showed great potential for antiparasitic treatment, given that it had high in vitro efficacy against monogenoideans and in vivo efficacy against the protozoon I. multifiliis. Because of the low concentrations of the essential oil (100 and 150 mg/L) that were tolerated by the fish and thus could be used in the therapeutic baths, the efficacy against monogenoideans was low. This indicates that there is a need for additional strategies for using this essential oil in antiparasitic treatments, since the concentrations that eliminate these ectoparasites are toxic for the hosts. Lastly, this was the first study on the antiparasitic activity of L. alba. Statement of Relevance The manuscript entitled "Antiparasitic activity of the essential oil of Lippia alba on ectoparasites of Colossoma macropomum (tambaqui) and its physiological and histopathological effects", represents original article on use of the essential oil of Lippia alba on ectoparasites of tambaqui, an important finfish of Amazon regio...

The present study investigated the effects of seasonal variation in parasites infracommunities of Hoplerythrinus unitaeniatus and Hoplias malabaricus from a tributary of Amazon River. For H. unitaeniatus and H. malabaricus, 11 parasite species were similar, and greatest parasite richness occurred during the rainy season. Ichthyophthirius multifiliis was the dominant parasite species for both hosts. In H. unitaeniatus, infection by Whittingtonocotyle caetei, Whittingtonocotyle jeju, Urocleidoides sp. and Anacanthorus sp. was higher during rainy season. Contracaecum sp., Procamallanus (Spirocamallanus) inopinatus, Nomimoscolex matogrossensis and Gorytocephalus spectabilis showed no seasonal pattern. For H. unitaeniatus, P. pillulare, Clinostomum marginatum and Argulus pestifer occurred only during dry season, while Trichodina sp., Dolops geayi, undetermined metacercariae and Posthodiplostomum sp. occurred only during the rainy season. In H. malabaricus, the prevalence of Urocleidoides eremitus was similar during the two seasons, but abundance was higher during the rainy season. Tetrahymena sp., C. marginatum, Dendrorchis neivai, undetermined metacercariae, Posthodiplostomum sp., Genarchella genarchella, Cystidicoloides sp., G. spectabilis, D. geayi, A. pestifer and Glossiphonidae gen. sp. occurred only during the dry season. However, Contracaecum sp. and P. (S.) inopinatus occurred during both seasons, but the prevalence of P. (S.) inopinatus was higher during the rainy season. Seasonal variation in this infection levels was due to the host's feeding behavior and habits and the availability of infectious forms of parasites with heteroxenic life cycles. The non-seasonal fluctuation detected are likely a result of the parasites biology, highly variable nature of this tributary of Amazon River and low abundance of parasites.

This work is the first study on parasitic fauna of Curimata cyprinoides Linnaeus, 1766 (Curimatidae) and the host-parasite relationship. The total of 154,740 parasites such as Ichthyophthirius multifiliis (Ciliophora), trophozoite of Spironucleus sp. (Hexamitidae), Urocleidoides sp. (Monogenoidea), Digenea gen. sp. and Polymorphus sp. (Polymorphidae) were collected. The component community showed low diversity (HB = 0.004 ± 0.020) and parasite species richness (1.4 ± 0.6). However, I. multifiliis and Urocleidoides sp. were prevalent and with higher intensity on the host population and also aggregated the distribution pattern. The occurrence of these ectoparasites in C. cyprinoides may be a consequence of its alimentary diet. Positive correlation between the abundance and size of I. multifiliis and the relative condition factor of the host were observed and discussed. These data represent increased knowledge of the biology of these parasites. Furthermore, this study expanded the geographic distribution of some parasite species for this new host from Brazil. Parasitos em Curimata cyprinoides (Pisces, Curimatidae) da Amazônia oriental, Brasil RESUMO. Este trabalho providenciou o primeiro estudo sobre a fauna parasitaria de Curimata cyprinoides Linnaeus, 1766 (Curimatidae) e relação hospedeiro-parasito. Foram coletados 154.740 parasitos, tais como Ichthyophthirius multifiliis (Ciliophora); trofozoíto de Spironucleus sp. (Hexamitidae); Urocleidoides sp. (Monogenoidea); Digenea gen. sp. e Polymorphus sp. (Polymorphidae). A comunidade componente apresentou baixa diversidade (HB = 0,004 ± 0,020) e riqueza de parasitos (1,4 ± 0,6). Ichthyophthirius multifiliis e Urocleidoides sp. apresentaram a maior prevalência e intensidade na população de hospedeiro e tiveram padrão de distribuição agregado. Em C. cyprinoides, a ocorrência desses ectoparasitos pode ser uma consequência da ampla variedade de sua dieta alimentar. Correlação positiva da abundância de I. multifiliis como o tamanho e fator de condição relativo dos hospedeiros foi observada e discutida. Estes dados representam um aumento do conhecimento sobre a biologia desses parasitos. Além disso, este estudo ampliou a distribuição geográfica de algumas espécies de parasitos para este novo hospedeiro no Brasil.Palavras-chave: ecologia, brânquias, peixe de água doce, Monogenoidea, protozoários.

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This study investigated the metazoan parasite fauna in Peckoltia braueri and Pterygoplichthys pardalis from a tributary of the Amazon River system, in northern Brazil. In P. braueri, 630 parasites were collected, belonging to Unilatus unilatus, Nothogyrodactylus sp., Genarchella genarchella, Proteocephalus sp., Gorytocephalus elongorchis, Dolops longicauda and Hirudinea gen. sp., with a dominance of monogenean species. In P. pardalis, 120 parasites were collected, belonging to U. unilatus, Acanthostomum gnerii and Gorytocephalus elongorchis, and this acanthocephalan was the dominant species. In both hosts, the parasites presented clumped distribution, high prevalence, low abundance, low Shannon diversity, and low species richness, with a predominance of helminth species. In P. braueri, host length was positively correlated with parasite species richness and Shannon index. There was no difference in the body condition of parasitized and non-parasitized fishes in either host. This was the first report of these parasites in P. braueri and P. pardalis. KEYWORDS: Digenea, diversity, helminths, parasites, freshwater fishes. Fauna de metazoários parasitando Peckoltia braueri e Pterygoplichthys pardalis (Loricariidae), bagres do nordeste da Amazônia brasileira RESUMOEste estudo investigou a fauna de parasitos metazoários em Peckoltia braueri e Pterygoplichthys pardalis de um tributário do sistema do Rio Amazonas, no Amapá, norte do Brasil. Em P. braueri foram coletados 630 parasitos das espécies Unilatus unilatus, Nothogyrodactylus sp., Genarchella genarchella, Proteocephalus sp., Gorytocephalus elongorchis, Dolops longicauda e Hirudinea gen. sp., com dominância das espécies de monogenoideas. Em P. pardalis foram coletados 120 parasitos das espécies U. unilatus, Acanthostomum gnerii e Gorytocephalus elongorchis, sendo este acantocéfalo a espécie dominante. Os parasitos em ambos hospedeiros apresentaram dispersão agregada, elevada prevalência, baixa abundância, baixa diversidade de Shannon e baixa riqueza de espécies, com predominância de espécies de helmintos. Em P. braueri, o comprimento dos hospedeiros apresentou correlação positiva com a riqueza de espécies de parasitos e o índice de Shannon. Não houve diferença entre a condição corporal de peixes parasitados e não parasitados para os dois hospedeiros. Este foi o primeiro relato desses parasitos para P. braueri e P. pardalis.

In vivo and in vitro antiparasitic activity of the essential oil of Lippia sidoides and blood and histological alterations were assessed in Colossoma macropomum (tambaqui). Essential oil concentrations of 10, 20, 40, 80, 160 and 320mg/L were assayed in vitro against monogenoideans Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri from fish gills. Lippia sidoides essential oil concentrations of 320 and 160mg/L were 100% effective against monogenoideans in 10min and 1h of exposure, respectively. However, the effectiveness of 100% concentrations of 80mg/L and 40mg/L occurred in 3 and 6h, respectively. In the in vivo tests, juvenile fish were submitted to 60min of baths with 10mg/L and 15min of baths with 20mg/L of the essential oil of L. sidoides. These therapeutic baths were not efficient against Ichthyophthirius multifiliis, and monogenoideans present in the gills of C. macropomum. In addition, 10 and 20mg/L of the essential oil of L. sidoides caused an anesthetic effect on the fish and did not influence total glucose and protein plasma levels; however, it decreased the number of total erythrocytes in fish exposed to the higher concentration of this essential oil. Severe alterations and irreversible damage were observed in the fish gills just after L. sidoides essential oil baths and after 24h of recovery. The most recurrent lesions found were hyperplasia and fusion of the lamellar epithelium, vasodilation, detachment of the gill epithelium and lamellar aneurism, epithelial breakdown with hemorrhage, congestion, edema and necrosis, proliferation of the mucous cells and chloride cells and lamellar hypertrophy. Therefore, since the essential oil of L. sidoides has in vitro antiparasitic activity and low concentrations of it have shown toxic effects, the bioactive potential of its main chemical components should be investigated, as well as more efficient forms of its administration in therapeutic baths in order to eliminate fish parasites.