Eggs hatching and oncomiracidia lifespan of Dawestrema cycloancistrium , a monogenean parasitic on Arapaima gigas

Methods for quantifying eggs and oviposition rate of Dawestrema cycloancistrium (Monogenea: Dactylogyridae), monogenean parasite of Arapaima gigas (Teleostei: Osteoglossidae)

“…A separate nylon net was used for water filtration and egg retention in each container. The mesh size of the nylon net was 20 μm, tested to guarantee the collection of all D. cycloancistrium eggs that measure 144.13 ± 13.62 μm in length and 40.40 ± 2.53 μm in width (Maciel et al , 2017). At the end of each filtration, each nylon net was washed, and the contents were transferred to 60-ml bottles with 5% formalin to preserve the eggs for subsequent sample processing.…”

“…At the end of each filtration, each nylon net was washed, and the contents were transferred to 60-ml bottles with 5% formalin to preserve the eggs for subsequent sample processing. The eggs are sticky due to the small elliptical and adhesive structures in the polar filament (Maciel et al , 2017), so the quantity of eggs retained in each nylon net was recorded by stereomicroscope immediately after collection.…”

“…In addition, egg morphology was used to identify D. cycloancistrium . Dawestrema cycloancistrium eggs are elongated ovals with a single long appendage at one pole; D. cycloancistrioides eggs are elongated ovals but with a proximal short polar filament; and D. punctatum eggs have an elongated shape with a terminal short filament at each pole (Kritsky et al , 1985; Maciel et al , 2017).

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“…The first egg morphology description for the three species of Dawestrema was presented by Kritsky et al (1985). Later, D. cycloancistrium eggs and oncomiracidia were described in more detail by Maciel et al (2017). The authors observed that the eggs are elongated ovals with a single long appendage at one pole measuring more than 11 times the length of the egg.…”

“…Oncomiracidia lifespan is 50 h and 58 h at 24°C and 27°C, respectively. Dawestrema cycloancistrium oncomiracidia access the skin of their hosts and larva can be seen in the mucus (Maciel et al , 2017).…”