Effects of temperature, salinity, desiccation and chemical treatments on egg embryonation and hatching success of Benedenia seriolae (Monogenea: Capsalidae), a parasite of farmed Seriola spp.

Abstract

The effects of temperature and salinity on the embryonation period and hatching success of eggs of Benedenia seriolae were investigated. Temperature strongly influenced embryonation period; eggs first hatched 5 days after laying at 28 degrees C and 16 days after laying at 14 degrees C. The relationship between temperature and embryonation period is described by quadratic regression equations for time to first and last hatching. Hatching success was >70% for B. seriolae eggs incubated at temperatures from 14 to 28 degrees C. However, no B. seriolae eggs embryonated and hatched at 30 degrees C and <2% of eggs hatched when incubated at 24 degrees C after transfer to 30 degrees C for 48 h. Embryonation period was similar for eggs incubated in sea water at 25, 30 and 35 per thousand salinity, but increased for eggs incubated at higher or lower salinities. When incubated at salinities ranging from 25 to 45 per thousand, more than 70% of B. seriolae eggs embryonated and hatched. Hatching success was lower at 20 and 50 per thousand salinity and few or no eggs hatched at 10 and 15 per thousand. Hatching of B. seriolae eggs can be prevented by desiccation for 3 min, by immersion in water at 50 degrees C for 30 s or by treatment with 25% ethanol for 3 min.

First record of Amphipolycotyle chloroscombrus Hargis, 1957 (Monogenea, Polyopisthocotylea, Gastrocotylidae) in the South Atlantic Ocean

“…According to ROHDE (2005), large hosts represent potential habitats with greater resources for parasites than smaller ones, thus being able to support high rates of infestation. Moreover, environmental factors such as temperature and salinity which influence the reproduction of the monogeneans also affect their abundance and occurrence in some areas during the year (ERNST et al, 2005;LUO;YANG, 2010;KHIDR et al, 2012). Therefore, the low prevalence of A. chloroscombrus on C. chrysurus must be attributed to the reproductive cycle of the parasite and/or the influences of environmental factors, as has also been reported by MUÑOZ and RANDAHAWA (2011) and ÖZER and KIRCA (2013) ( Table 2).…”

Some pathophysiological insights into ovarian infestation by Myxobolus sp. (Myxozoa: Myxosporea) in Clarias gariepinus (Clariids: Silurids) from Bénin (West Africa)

“…was reported by Gbankoto et al (2001bGbankoto et al ( , 2003 and showed that the infection rate may change significantly among seasons. It is has been also shown that parasite prevalence could vary in function with seasons (Ernst et al 2005;Khidr et al 2012). Molnar (1998) claimed that the major seasonal differences were found in parasite prevalence with markedly lower numbers of infected fish specimens in summer months than in spring months.…”

Bioavailability and pharmacokinetics of a praziquantel bolus in kingfish Seriola lalandi

“…Among gill flukes, Hetaraxine heterocerca and Zeuxapta japonica infect yellowtail and amberjack in Japan, whilst Zeuxapta seriolae infect kingfish in Australia and New Zealand plus amberjack in the Mediterranean (Grau et al 2003, Montero et al 2004). Management of these parasites can be expensive: up to 20% of the total production cost of Japanese Seriola species has been attributed to B. seriolae management alone (Ernst et al 2005). Parasite management strategies are therefore an important aspect of Seriola species culture; ideally these strategies should incorporate effective treatments that are administered under the most efficient regimen.…”