Molecular Identification Of The Anisakid Larva From The Eel In The South China Sea

Based on the observation of morphological characters,1068larvae of nematodescollected from eel like Uroconger lepturus, Parabathymurus macrophthalmus, Chlopsisfierasfer, Myrophis macrophthalmus, and Rhynchocymba nystromi were picked out, exceptnematodes of the genus Anisakis.The nematodes were identified by PCR-PFLP. After theamplification of ITS region of rDNA, the PCR products were digested by HinfI and RsaIenzymes, respectively, followed by agarose gel electrophoresis analysis, three differentelectrophoretic patterns were obtained. The selected samples were sequenced. The sequencingresults were compared with the data of Genbank, three species were identified. Throughphylogenetic analysis, we found that Y1, Y3and Y5clustered in the branch of the genusHysterothylacium. Y1clustered with Contracaecum muraenesoxi, and Y5clustered withRaphidascaris trichiuri, which indicated that Y1represents Contracaecum muraenesoxi，Y5represents Raphidascaris trichiuri, the result coincides with sequence aligment. Because Y3clustered with the group of Hysterothylacium, it was identified as Hysterothylaciumsp.NH-2012. However, it is proved that Contracaecum muraenesoxi is the synonym ofHysterothylacium amoyense. Therefore, the three species are Hysterothylacium sp.NH-2012,Hysterothylacium amoyense and Raphidascaris trichiuri.The statistics shows that, Hysterothylacium sp. NH-2012is the dominant species in thethree parasitic nematodes collected from the South China Sea, followed by Hysterothylaciumamoyense and Raphidascaris trichiuri. The number distribution in fishes is as follows:Uroconger lepturus is566/37/9，Parabathymurus macrophthalmus is192/6/5， Chlopsisfierasfer is100/12/0， Myrophis macrophthalmus is15/8/0， Rhynchocymba nystromi is88/9/0， Dysomma anguillaris is3/0/1， Rhynchocymba ectenura is6/1/1， Myrophis cheniis2/0/0， Pisoodonophis boro is3/1/1， Rhynchoconger ectenurus is2/0/0， Muraenesoxtalabonoides is0/1/0。 Among the average infection intensity in Hysterothylacium sp.NH-2012, the higher average infection intensity is35of Uroconger lepturus,21ofRhynchocymba nystromi，25of Chlopsis fierasfer，48of Parabathymurus macrophthalmus.However the average infection intensity of Hysterothylacium amoyense and Raphidascaris trichiuri are relative low (with a range from1to3.25).Eel is the important economic fish in China, this is the first research about the speciesidentification of larvae nematodes collected from the eel in the south China Sea, whichprovided the scientific basis for the development of the eel, artificial cultivation and thecontrol of fish parasites.