Oliveira, E.C., E.C. Pereira, R.A. Cajado, L.V.F. da Silva & L.L. Corrêa. (2021). Description of the life cycle of Dolops discoidalis (Bouvier, 1899) (Branchiura: Argulidae), a parasite of the fish species Rhytiodus argenteofuscus (Kner, 1858) from the Brazilian Amazon. Annals of Parasitology. 67(3):473-482.

421457

Oliveira, E.C., E.C. Pereira, R.A. Cajado, L.V.F. da Silva & L.L. Corrêa

2021

67(3):473-482.

Publication

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The genus Dolops (Audouin, 1837) is endemic among ectoparasites present in fish, with nine species described in Brazil, five of which are from the Amazon region. Among the genus, the species Dolops discoidalis (Bouvier, 1899) stands out due to its high prevalence of parasitism in Amazonian fish. The present study aims to characterize the development phases of D. discoidalis. The parasites were obtained from infected fish species Rhytiodus argenteofuscus from a natural environment, kept in polyethylene experimental boxes (500 liters). The physical-chemical parameters of the water (pH, electrical conductivity, dissolved oxygen and temperature) were monitored daily. A total of 30 egg layings were analyzed. After identification of the oviposition, the eggs were transferred to another container containing water (0.5 liters). The number of eggs was recorded, with observations made in stereomicroscopic and photographic records until hatching occurred. The egg layings exhibited differences in colour throughout their development. On the seventh day, the embryos exhibited visible ocelli and on the 17th day the hatching period began. Hatching occurred in batches, with around 5–10 hatches/day/laying. However, peak hatching was recorded on the 19th day of the cycle. Therefore, the cycle of D. discoidalis comprised a total period of 17–22 days at 28ºC, with hatching in batches and pigmentation of the eggs observed close to hatching. Newly hatched parasites did not survive for more than 24 hours in the absence of the host. This study contributes to knowledge of the biology of D. discoidalis, and adds to information regarding possible studies into its control.

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