New finding on a migratory bird, the fowl tick Argas (Persicargas) persicus (Oken, 1818), in Italy

Abstract

Migratory birds reach Europe from sub-Saharan Africa, and some avian species may harbor and transport infected ectoparasites, mainly ticks, native to the territories of departure. In 2022, a project focused on identifying the introduction of pathogens in Italy from Africa via migratory birds represented an important opportunity to investigate this particular route of tick dispersal. Among ticks collected from migratory birds on the island of Ventotene, Latium Region, we found one larva of a soft tick on a common whitethroat (Curruca communis) that was morphologically and molecularly identified to the species level as Argas (Persicargas) persicus (Oken 1818). This study reports the fifth detection of this species in Italy; therefore, it is considered very rare. Further monitoring programmes should be implemented to better monitor the spread of this species and possibly update its distribution.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10493-024-00975-8.

Introduction

Birds are known to play a crucial role in the passive dispersion of ticks due to their seasonal migratory journeys. Among the different ornithophilic tick genera, nidicolous ones, particularly those belonging to the Argas genus, can host a plethora of pathogens throughout all their developmental stages (Hoogstraal 1985). Every spring, numerous migratory birds arrive in the Mediterranean region from Africa, mainly from the northern territories (short-distance migrants) or from sub-Saharan countries (long-distance migrants). These birds play a major role in the distribution of ticks and their pathogens along their migratory routes (Hasle 2013); however, little to no information is known about the diversity of the tick species they carry (Toma et al. 2021; Hornok et al. 2022). As part of a project aimed at monitoring the introduction of tick-borne pathogens via migratory birds, a larva of Argas (Persicargas) persicus (Oken 1818) (hereinafter A. persicus), also known as the fowl tick, was found parasitizing a trans-Saharan migratory bird. The first report of this species in Italy was in Trieste, Northeast, in 1930 from nests of pigeons (Columba livia) (Starkoff 1958). A second finding occurred in the surrounding area of Lago di Como, Northwestern Italy, in 1984 on a great tit (Parus major) (Walter and Massa 1987); in 2010, 13 specimens were found in Sicily, a province of Trapani, near nests of magpie (Pica pica) (Pantaleoni et al. 2010); and, last, in 2023 in the Maremma Regional Park, Tuscany, in nest boxes of migratory bird species (Monti et al. 2023). Concerning its Western-Palearctic areal, this tick has been reported in the southern Mediterranean side, namely in Egypt and Libya, eastward in the Middle East, in Anatolia, and in the Balkans reaching Slovakia in the North and westward in Italy, Corsica, and Spain (Pantaleoni et al. 2010); it has also been recorded in Romania in poultry shelters (Coipan et al. 2011). In Africa, A. persicus is known to be spread in the tropics and sub-tropics in association with poultry, (Walker et al. 2003). This species is a vector of bacteria causing avian spirochetosis in wild birds and poultry, but has also been found to harbour many other bacteria and viruses (Duan et al. 2022).

In this paper we describe the new findings and the identification of this species, collected from a migratory bird on the island of Ventotene (Latium region), which represents the fifth record of A. persicus in Italy, and the first one on a bird during active migration.

Materials and methods

The Argas specimen reported in this study was collected during spring bird-ringing activities on Ventotene Island on 20 May 2022 from a 2nd-year female of common whitethroat (Curruca communis, Sylviidae, Passeriformes). This bird species is an obligate trans-Saharan migrant which has its migratory peak in Italy between the second half of March and the end of May, and uses the small islands in the Mediterranean (such as Ventotene) uniquely as a stop-over site (Spina and Volponi 2008).

The specimen was picked up using tweezers, stored in an Eppendorf tube containing 70% ethanol, identified morphologically using the available identification keys (Manilla 1998; Pfäffle and Petney 2017), and photographed using Z-stack imaging microscopy. The images were acquired at the Science Department of Roma Tre University with a Zeiss Axio Zoom V16 stereomicroscope equipped with a Plan-NEOFLUAR Z 1x objective lens and an Axiocam 503 digital color camera at 112× magnification. The images were postprocessed using Photoshop CC 2020 software. This technique provides high-quality images that allow the observation of morphological characters that would otherwise be difficult to see. After this step, the tick was processed using a 5 mm steel bead and a Tissue-lyser LT (Qiagen, Germany) at 30 Hz for 3 min and then centrifuged at 4 °C and 10,000 × g for 5 min. Nucleic acids were extracted from the clarified supernatants of the homogenates with the BioSprint 96 One-For-All Vet Kit (INDICAL BIOSCIENCE) according to the manufacturer’s protocol. The DNA sample was analyzed through amplification and sequencing of a portion of two mitochondrial genes, 12 S ribosomal DNA (rDNA) and cytochrome C oxidase subunit I (COX1 mtDNA) (Table S1) (Folmer et al. 1994; Beati and Keirans 2001). The PCR products were purified and directly sequenced at Eurofins Genomics (Ebersberg, Germany). The sequences obtained were compiled using DS Gene v1.5 software (Accelrys, Inc., San Diego, CA, USA) and analyzed using NCBI’s Basic Local Alignment Search (BLAST), which is performed with the parameter of highly similar sequences (Megablast) for the identification of tick species (Altschul et al. 1990) (Table 1). To ascertain the degree of similarity or diversity, alignments of partial sequences of different Argas species retrieved from GenBank (http://www.ncbi.nlm.nih.gov/) were performed using the DS Gene v1.5 software (Accelrys Inc., San Diego, CA, USA). A phylogenetic analysis was conducted using MEGA11 (Tamura et al. 2021) with the Maximum Likelihood Tamura 3-parameter model (Tamura 1992) based on the COX1 and 12 S rRNA genes (Fig. 1 and Fig. S1). The percentage displayed at each node represents the bootstrap value (derived from 1000 replicates) (Felsenstein 1985). The GenBank accession numbers of the sequences employed in the analysis are provided alongside the tree. The sequences of Dermanyssus gallinae (COX1: NC05303, and 12 S: MW044168) were used as the outgroup (Fig. 1 and Fig. S1).

Table 1.

BLAST analysis results of the obtained sequences against Genbank database sequences

Argas persicus from Ventotene GenBank accession No.	Gene target	Most homologues sequences identified by Blast analysis	Species (origin)	% of identity (% cover)
PP262118	12 S	ON800828	Argas persicus (Chile)	100% (100%)
		KJ133581	Argas persicus (Kenya)	100% (100%)
		from OP331233 to OP331239	Argas persicus (Algeria)	100% (90%)
		OM368319	Argas persicus (China)	99,72% (100%)
		OM368320	Argas persicus (China)	99,5% (100%)
PP259541	Cox1	ON800828	Argas persicus (Chile)	99,42% (100%)
		OM368319	Argas persicus (China)	99,27 (100%)
		KJ133581	Argas persicus (Kenia)	99,27 (100%)
		from OP326579 to OP326584	Argas persicus (Algeria)	99,56 (98%)

Fig. 1.

Argas (Persicargas) persicus (Oken, 1818) larva: dorsal view on the left, ventral view on the right

Results

The specimen was morphologically identified as A. persicus according to the following characteristics. The specimen was approximately 2 mm in length and width; the idiosome was subcircular with the base of the capitulum and not prolonged anteriorly. The squamous area was small, rounded, and located in the center of the body in a dorsal position. Dorsal chaetotaxis revealed 15 pairs of marginal setae, 3 pairs surrounding the squamous area, 3 on each anterior quadrant and 7 on each posterior quadrant; the length and width were approximately 2 mm (Fig. 2). In accordance with the morphological identification, BLAST analysis of COX1 and 12 S rDNA sequences from Ventotene specimens showed > 99% nucleotide homology with A. persicus sequences available in GenBank (Tab. S2). A phylogenetic analysis was conducted using 12 S rDNA and COX1 sequences of Argas species available on the GenBank database. The resulting Maximum Likelihood phylogenetic trees showed that Ventotene specimens shared the same clade with haplotypes of A. persicus from several different countries (Fig. 1 and Fig.S1). The GenBank accession numbers of the original sequences acquired in this study are PP262118 (12 S rDNA) and PP259541 (COX1).

Fig. 2.

Phylogenetic tree based on the partial sequences of the COX1 gene of 28 nucleotide sequences of Argas species. The tree was constructed by using the Maximum Likelihood method, using the Tamura 3-parameter model. A total of 656 positions were considered in the final dataset. Evolutionary analyses were conducted in MEGA11 (Tamura et al. 2021). GenBank accession number is provided next to each tick species name. The original sequence PP259541 obtained in the present study is indicated in the tree. Dermanysus gallinae was used as outgroup

Discussion and conclusion

Argas persicus is a soft tick from the family Argasidae that is known to parasitize arboreal nesting birds but, successfully adapted to coexist with fowl has been carried to many parts of the world where it occurs most commonly associated with poultry and domestic birds (Hoogstraal 1985; Muñoz-Leal et al. 2018).

This species, which originates from central Asia, is now distributed worldwide due to various ecological and environmental factors (Hoogstraal 1985; Pantaleoni et al. 2010). It thrives in a fairly wide range of climate conditions, from desert to Mediterranean temperate climates to rainforests (Walker et al. 2003), with a preference for warmer climates, such as the tropics. This preference could explain the scarce presence of this species in Italy, where it is described in the literature with extremely sporadic reports. Hence, based on the nonbreeding areas and the spring migratory route of the host bird species C. communis, the ticks collected in this study most likely originated from the African continent (BirdLife International 2019). Numerous studies have demonstrated that a large fraction of trans-Saharan passerines, like the C. communis, leave the coasts of the African continent and reach Ventotene and the other Pontine Islands directly from the African coasts, after a one-night non-stop flight during the spring migration towards their breeding grounds in Europe (Pilastro and Spina 1997). Then, in addition to being rare in Italy, A. persicus has never been described on the island of Ventotene, where sample surveys for free-living ticks (Toma et al. 2021; Mancuso et al. 2023), on the few farmyard animals (poultry, geese, rabbits, a cow, and a sheep) and poultry shelters on the island, have not yielded any results. (Toma L., unpublished data).

Despite being strongly influenced by environmental conditions, A. persicus usually displays the typical life cycle of an argasid tick, as it has 4 nymphal stages before molting into the adult stage (Walker et al. 2003). This endophilic tick has a nidicolous lifestyle and lives in wood crevices underneath the bark at roosting sites or inside birds’ nests under the debris of nesting materials. Generally, associated with domestic fowl, it is not uncommon for this species to live in chicken coops. It is a nocturnal animal, as nymphs and adults preferably feed at night when the hosts are resting. After the blood meal, adult females lay batches of eggs, from which larvae emerge in approximately three weeks and soon find a host to feed on from 5 to 10 days (Barker and Walker 2014). Regardless of the life stage, this species hides in the fissures of the wood to molt, which occurs after each blood meal. Nymphs feed for a shorter period of time than adults, from 5 min to a few hours (Walker et al. 2003). Argas persicus is the main vector of the bacteria Borrelia anserina, the causative agent of avian spirochaetosis, and Aegyptianella pullorum (Gothe et al. 1967, 1981). Furthermore, the tick is known to transmit Salmonella gallinarum/pullorum (Gothe 1967). This tick was found to be positive for Rahnella aquatilis, Enterobacter cloacae, and Chryseobacterium meningosepticum (Stefanov et al. 1975; Montasser 2005; Manzano-Román and Díaz-Martín 2012) and was also suspected to be involved in the circulation of West Nile virus (Estrada-Peña 2017). This new finding of A. persicus in Italy, where the species is considered very rare,, together with previous findings in northern Italy, Sicily (Pantaleoni et al. 2010) and Tuscany (Monti et al. 2023), highlights the important ecological significance and the potential impact of these ticks on health. The finding over time that several specimens of the tick were at different life stages in seminatural contexts suggests that it may have successfully completed its life cycle after being introduced into Italy. Thus, further surveillance programs should be implemented to monitor the spread of this tick species and update its distribution.

Electronic supplementary material

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Author contributions

M. M. and L.T.: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing original draft; F.C.: Investigation, Methodology of image acquisition, Data curation; E.M.: Investigation, Methodology, Data curation; M. D.i L.a and F.S.: Methodology review and editing; Federica Monaco: Supervision, Funding acquisition. All the authors have read and approved the final version of the manuscript.

Funding

This research was framed by the project titled ‘Emerging and re-emerging zoonoses along the routes of migratory birds. An integrated approach to investigate the potential route of introduction and spread’ (IZS AM 04/19 RC) funded by the Italian Ministry of Health and partially funded by the EU within the NextGeneration EU-MUR PNRR Extended Partnership initiative on Emerging Infectious Diseases (Project no. PE00000007, INF-ACT).

Data availability

We declare all data are being provided within this manuscript.

Declarations

Author contribution

M. M. and L.T.: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing original draft; F.C.: Investigation, Methodology of image acquisition, Data curation; E.M.: Investigation, Methodology, Data curation; M. D.i L.a and F.S.: Methodology review and editing; Federica Monaco: Supervision, Funding acquisition. All the authors have read and approved the final version of the manuscript.

Competing interests

The authors declare no competing interests.