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Home » Archive » 2021 » Veterinary Session

Veterinary session

Molecular taxonomic investigations of ticks collected from birds in Malta
Cutajar Bernard - year 6
University of Veterinary Medicine Budapest, Department of Parasitology and Zoology
Supervisor: Dr. Sandor Hornok

Abstract:

The Maltese Archipelago is situated in the middle of the Mediterranean Basin, between Europe and Africa, in the Central European route (or the Adriatic Flyway) of bird migration. Along this migratory route, the Maltese islands represent the last stopover site for birds heading from Europe to their wintering grounds in Africa, and it is also the first land where birds arrive from Africa when entering Europe. Migratory birds are important long-distance carriers of ticks, and thus can play an important role in intra- and intercontinental dispersal of tick-borne pathogens. Nevertheless, data on tick species associated with birds are not available from Malta.

In this study, birds mist-netted for ringing at BirdLife Malta were examined for the presence of ticks between September, 2019 and May, 2021. During this period 19,637 birds were handled on four premises (including woodland, wetland and garrigue). Ticks were collected and stored in ethanol until species identification based on standard morphologic characters and molecular taxonomic analyses. Three conventional PCRs were used which amplify (1) the cytochrome c oxidase subunit 1 (cox1) gene, (2) the 16S rRNA gene or (3) the 12S rRNA gene, respectively. The PCR products were sequenced and then compared to GenBank data with the BLASTn program.

During the study period, individuals of 23 bird species were found tick-infested, from which 113 hard ticks (Acari: Ixodidae) were collected. The majority of their collected life cycle stages were nymphs, but nine larvae and one female were also found. These ticks belonged to nine species: Ixodes cumulatimpunctatus (n=1) Ixodes ricinus (n=2), Ixodes acuminatus (n=2) Ixodes frontalis (n=5), Ixodes festai (n=1), Amblyomma marmoreum (n=8), Hyalomma rufipes (n=78), Hyalomma marginatum (n=7) and Hyalomma lusitanicum (n=1). Eight Hyalomma sp. ticks could only be identified on the genus level. Regarding seasonality, all Palearctic Ixodes species were carried by birds exclusively in the autumn (i.e., north to south), whereas Hyalomma rufipes (with predominantly Afrotropical distribution) was exclusively collected in the spring (i.e., carried south to north). Two identified tick species, A. marmoreum and I. cumulatimpunctatus are only indigenous in the Afrotropical zoogeographic region. This is the first finding of the latter tick species in Europe, and four tick species were found for the first time in Malta.

Compared to bird tick studies reported from Central and Western Europe, the estimated frequency (prevalence) and the maximum level (intensity) of tick infestation was low among birds in Malta, but the species diversity was unexpectedly high. It is not surprising that no Dermacentor or Rhipicephalus species were collected from birds, as these very rarely associate with avian hosts. On the other hand, Haemaphysalis species are common on birds north of the Mediterranean Basin, but they were not found among ticks collected during this study in Malta.



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