Comparative susceptibility of two different genetic types of tilapia to Neobenedenia sp. (Monogenea)

Abstract

Two different genetic types of tilapia, Mozambique tilapia Oreochromis mossambicus (MT), and Pargo-UNAM (PU; a synthetic hybrid whose genetic composition is 50% Florida red tilapia, 25% Rocky Mountain tilapia, and 25% red variant Oreochromis niloticus), were acclimatized to salinity and exposed to seawater from the Gulf of Mexico off the port of Veracruz, Mexico. Both fish types were infected by the monogenean ectoparasite Neobenedenia sp. and were killed within 2 to 3 wk. A crude worm extract was prepared from whole specimens collected during the original outbreak and used to immunize naïve hosts of the same 2 types of tilapia. Immunized fish were then exposed to seawater, which resulted in Neobenedenia sp. infection. Immunization did not confer any protection against Neobenedenia sp. infection. However, the experiment enabled detailed analysis of the dynamics of infection and comparison of the effects of the parasite on the 2 host types. Although both tilapia types exhibited similar resistance to infection (as they harbored similar parasite burdens in the early phase of infection), PU is less tolerant to Neobenedenia sp., as a mean parasite abundance of ca. 50 worms fish -1 killed all hosts within a fortnight, while 22% of MT survived up to 3 wk, harboring a mean parasite abundance of ca. 900 worms fish -1. Our results suggest that, as reported elsewhere, Neobenedenia sp. could negatively affect mariculture off the Mexican coast of the Gulf of Mexico.

A global review of problematic and pathogenic parasites of farmed tilapia

“…Kishimori et al 371 noted a specific antibody response to Neobenedenia in O . mossambicus , although Rubio‐Godoy et al 378 found that injecting purified worm extracts did not decrease Neobenedenia infection in tilapia. Ongoing research is likely to focus on management and decreasing the effects of infections on cultured fish and of control on the costs of production 386…”

“…was reported from O. mossambicus and O. niloticus hybrids in Mexico's Atlantic coast. 378 Invasive O. mossambicus and Tilapia mariae in brackish water in Australia are parasitised by N. girellae (Hargis, 1955; M. Deveney, unpublished data; Figure 10a).…”

Helminth parasites of finfish commercial aquaculture in Latin America

“…Species of the family Capsalidae are also important parasites on tilapia cultured in seawater (Conroy & Conroy, 2008; Rubio-Godoy et al . 2011; Shinn et al ., 2015). Several authors have shown that the main helminth species affecting fish health in intensive closed-system culture are monogeneans.…”

“…Gyrodactylus cichlidarum is widely distributed in Latin America (Brazil, Colombia, Ecuador, Honduras, Mexico, Puerto Rico) and has been detected in Nile tilapia ( Oreochromis niloticus ), blue tilapia ( O. aureus ), Mozambique tilapia ( O. mossambicus ) and hybrid red tilapia ( O. mossambicus × O. urolepis ) (Bunkley-Williams & Williams, 1994; Conroy, 2001; Jiménez, 2007; García-Vásquez et al , 2011; Lacerda et al , 2013; Salgado-Maldonado & Rubio-Godoy, 2014; Paredes-Trujillo et al , 2016a). Gyrodactylus cichlidarum is especially harmful to tilapia kept in ponds, attacking mainly the skin and fins (García-Vázquez et al , 2011; Paredes-Trujillo et al ., 2016a). Gyrodactylus niloticus has been recorded from Mexico on O. aureus, O. mossambicus and O. niloticus (Hernández-Martínez, 1992; López-Jiménez, 2001; Salgado-Maldonado et al , 2005).…”

“…This was verified experimentally by Rubio-Godoy et al . (2011), who exposed O. mossambicus and Pargo-UNAM (a synthetic hybrid whose genetic composition is 50% Florida red tilapia, 25% Rocky Mountain tilapia, and 25% red variant O. niloticus ) to seawater collected at Veracruz on the Gulf of Mexico. Both tilapia types became infected by Neobenedenia sp., and most of the fish died within a fortnight following exposure.…”