Morpho-molecular characterization of Gyrodactylus parasites of farmed tilapia and their spillover to native fishes in Mexico

Abstract

Translocation of fishes for aquaculture has resulted in the co-introduction of some of their parasites. African cichlid fishes, generically called “tilapias” have been introduced worldwide, along with their monogenean parasites. In a nation-wide survey, we characterised monogeneans of the genus Gyrodactylus infecting farmed “tilapia” throughout Mexico. We also collected native fishes around farms, to look for potential parasite spillover from cultured fishes. Monogeneans were identified taxonomically using morphological and molecular characters. Originally African, pathogenic Gyrodactylus cichlidarum was recorded in every farm surveyed, infecting different “tilapia” varieties, as well as three native cichlid fish species. Previously, we had shown that G. cichlidarum also infects native, non-cichlid fishes in Mexico. We also recorded that Gyrodactylus yacatli is widely distributed in Mexico, infecting cultured “tilapia” and native fishes; and present data indicating that this is a further translocated African parasite. A third, unidentified gyrodactylid infected farmed and native fishes in Chiapas, southern Mexico; we describe the new species as Gyrodactylus shinni n. sp., and provide evidence that this is a third monogenean translocated with African fish. The wide distribution of exotic parasites co-introduced with “tilapia” and their spillover to native fishes may have an important impact on the ichthyofauna in Mexico, one the world’s megadiverse countries.

The macroparasite fauna of cichlid fish from Nicaraguan lakes, a model system for understanding host–parasite diversification and speciation

“…As recently shown by Ref. 62 the fact that exotic parasites can be co-introduced with tilapia may determine their spillover and negative impact to the native fish fauna. Furthermore, our results show that tilapias acquired native parasites such as the widespread acantocephalan N. costarricense and several trematodes of the genus Saccocoelioides .…”

“…As mentioned before, we found the African monogenean C. sclerosus , but only in the African tilapia, and not yet on a native cichlid. This parasite has spread around the world together with farmed tilapia 62 – 65 . Tilapias were introduced in several Nicaraguan crater lakes and in both great lakes since the 50’s 61 .…”

Transmission dynamics of ectoparasitic gyrodactylids (Platyhelminthes, Monogenea): An integrative review

“…New evidence indicates that translocation of fishes due to aquaculture, like carp, tilapia and trout, has resulted in the co-introduction of their gyrodactylid species (García-Vásquez et al ., 2021) which may promote switching to native fishes. This is the case of various cichlids from three genera; Coptodon , Sarotherodon and Oreochromis (referred to generically as ‘tilapia’) and their Gyrodactylus pathogens like G. cichlidarum which was initially described from Sarotherodon galilaeus , but later was recorded in several farmed and wild cichlids on all continents except Antarctica (García-Vásquez et al ., 2010; Soler-Jiménez et al ., 2017; Zhang et al ., 2019).…”

“…For example, at least three African gyrodactylids translocate into Mexico with their ‘tilapia’. Today, these worms are widely distributed throughout the country infecting farmed and feral ‘tilapias’ but also native poeciliids fishes (García-Vásquez et al ., 2021).…”

Internal Transcribed Spacer (ITS) Region as Molecular Marker for Parasite Identification in Aquaculture: A Review

“…Gyrodactylids ITS1-fm (5'-TAG AGG AAG TAC AAG TCG -3') and ITS2-rm (5'-GCT YGA ATC GAG GTC AGG AC-3′) internal primers ITSR3A (5′-GAG CCG AGT GAT CCACC-3′) and ITS4.5 (5′-CAT CGG TCT CTC GAACG-3′) [33] No. NC5 primer (forward: 50-GTA GGT GAA CCT GCG GAA GGA TCA TT-30) and the NC2 primer (reverse: 50-TTA GTT TCT TTT CCT CCG CT-30)…”