Morphological and Molecular Identification of Mullet Helminth Parasite Fauna from Ganzirri Lagoon (Sicily, Southern Italy)

Abstract

Mullets (Osteichthyes: Mugilidae) are a euryhaline species widely distributed all over the world, thus representing an excellent study model for host-parasite interactions. From March to June 2022, 150 mullets, belonging to Chelon labrosus (n = 99), Chelon auratus (n = 37), and Oedalechilus labeo (n = 14) species, were caught to identify the helminth parasite fauna of the different mullet species present in the Ganzirri Lagoon (Messina, Sicily, Italy). A parasitological evaluation of the gastrointestinal tract (GIT) was carried out with a total worm count technique (TWC) to detect helminth presence. All collected parasites were stored in 70% ethanol until morphological evaluation, and frozen at -80 °C for subsequent molecular analysis, using 28S, ITS-2, 18S primers. The morphological evaluation allowed for the identification Acanthocephalan parasites (Neoechinorhynchus agilis) from two C. labrosus specimens. Sixty-six samples were positive for adult digenean trematodes (C. labrosus, 49.5 %; C. auratus, 27%, and O. labeo, 50%), molecularly identified as Haploporus benedeni. This study represents the first survey of helminthic parasite fauna of mullets from the south of Italy. The presence of Hydrobia sp. in the stomach contents of mullets allowed us to infer the H. benedeni life cycle in the Ganzirri lagoon.

Keywords: Acanthocephalan; Chelon auratus; Chelon labrosus; Oedalechilus labeo; trematode.

Figure 1

Neoechinorhynchus agilis cranial and posterior end: (A) proboscis (P), proboscis receptacle (R), lemnisci (L1, L2); (B) proboscis (P), proboscis receptacle (R), hook systems (H); (C) N. agilis male posterior end: seminal vesicle (SV), Saefftigen’s pouch (SP), bursa (BU), calotte (CA), genital pore (GP).

Figure 2

Mean abundance of Haploporus benedeni found in all three mullet species: CL: Chelon labrosus; CA: Chelon auratus; OL: Oedalechilus labeo. Each datum is shown as mean ± SD. Letters are only present in the case of significant statistical differences. Different letters refer to significant differences between different species. Differences were considered significant when p < 0.05.