Molecular and morphological studies on Contracaecum rudolphii A and C. rudolphii B in great cormorants (Phalacrocorax carbo sinensis) from Italy and Israel

Abstract

The distribution of parasites is shaped by a variety of factors, among which are the migratory movements of their hosts. Israel has a unique position to migratory routes of several bird species leaving Europe to winter in Africa, however, detailed studies on the parasite fauna of birds from this area are scarce. Our study investigates occurrence and distribution of sibling species among Contracaecum rudolphii complex in Phalacrocorax carbo sinensis from Italy and Israel, to acquire further information on the geographical range of these species to gain deeper knowledge on the ecology of these parasites and their bird host. A total of 2383 Contracaecum were collected from the gastric mucosa of 28 great cormorants (18 from Israel and 10 from Italy). A subsample was processed for morphological analyses in light and scanning electron microscopy (SEM), and for molecular analyses through amplification and sequencing of the ITS rDNA and the cox2 mtDNA, and through PCR-RFLP. All the 683 Contracaecum subjected to molecular identification belonged to C. rudolphii s.l., (300 C. rudolphii A and 383 C. rudolphii B). SEM micrographs provided, for the first time, details of taxonomic structures in male specimens from both sibling species, and the first SEM characterization of C. rudolphii B. This work presents the first data on the occurrence of sibling species of C. rudolphii in Israel and provides additional information on the distribution of C. rudolphii A and B in Italy, confirming the high prevalence and intensity of infection observed in Ph. carbo sinensis from other Italian areas.

Morphological and molecular data on acuariid nematodes in European great cormorants (Phalacrocorax carbo sinensis) and pygmy cormorants (Microcarbo pygmaeus)

“…This overall low intensity may be related to possible mechanisms of competitive interactions with other species of parasitic helminths, as suggested by Dezfuli et al 25 ; in fact, in the same Ph. carbo sinensis analyzed in the present work, high intensity values of the anisakid nematodes Contracaecum rudolphii A and Contracaecum rudolphii B were also observed 26 ; the same M. pygmaeus analyzed in the present work, were infected also by Amirthalingamia macracantha (Joyeux and Baer 1935) (Cestoda) 27 .…”

“…In other groups of bird parasites (e.g. in Anisakidae of the genus Contracaecum Railliet & Henry, 1912), the use of molecular data has helped to reveal hidden genetic diversity 26 ; however, as mentioned earlier, few sequence data of acuariids are available in public databases: for the genus Cosmocephalus , such data are available only for the species C. jaenschi . Nevertheless, the wide distribution of this species has also been associated to its ecology and to the wide-ranging ability of its hosts 7 , 31 .…”