On the way between Africa and Europe: Molecular taxonomy of ticks collected from birds in Malta

Abstract

The Maltese Archipelago is situated in the middle of the Mediterranean Basin, between Europe and Africa, therefore representing an important stopover site for migratory birds between these two continents. Despite this, up-to-date information is not available on tick species associated with birds in Malta. Therefore, in this study, birds mist-netted for ringing by BirdLife Malta were examined for the presence of ticks between September, 2019 and May, 2021. Ticks were identified morphologically and molecularly, using three genetic markers. During the study period, 57 individuals of 22 bird species were found tick-infested, from which altogether 113 ixodid ticks were collected. The majority of developmental stages were nymphs, but 13 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), one species of the Amblyomma marmoreum complex (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 H. rufipes (with predominantly Afrotropical distribution) was exclusively collected in the spring (i.e., carried south to north). Two tick species that occurred on birds in Malta, i.e., a species of the A. marmoreum complex 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 identified for the first time in Malta. In conclusion, the diversity of tick species regularly arriving in Europe from Africa is most likely higher than reflected by data obtained in Mediterranean countries of mainland Europe. Most notably, ticks of the genus Amblyomma appear to be underrepresented in previous datasets. Ticks of the subgenus Afrixodes (represented by I. cumulatimpunctatus) might also be imported into Europe by migratory birds.

Keywords: 12S rRNA gene; 16S rRNA gene; Amblyomma; Hyalomma; Ixodes; cox1 gene.