The present study reports morphological identification and prevalence of the soft tick A. persicus collected from traditional farms raising hens and other domestic birds from east of Algeria. Argas persicus spread widely in the world, adapted to diverse climatic conditions and closely associated to domestic chickens (Pfäffle and Petney 2017). In Algeria, few surveys have been conducted on the morphological identification, geographic distributions, and economic importance of this soft tick species infesting domestic birds from both traditional and industrial farms. Argas persicus has been reported in different bioclimatic regions of Algeria, including Mostaganem and Annaba (coastal areas), Setif, M’sila, Medea, Guelma (inland regions), and Tamanrasset (Sahara region) (Lafri et al. 2017; Boucheikhchoukh et al. 2018; Lafri et al. 2018; Ouchene et al. 2020; Nahal et al. 2021). As compared to the prevalence rate of farm infestation from the current study, higher rates have been reported in central-northern of Algeria (Media region), as well as in other regions worldwide (e.g., Pakistan) (Ouchene et al. 2020; Zahid et al. 2021). Distinctly variable infestation rates (at level of hosts, farms or different regions) have been reported worldwide. Various factors such as study design, sample size, duration and period of sampling (seasons), breeding system of chickens as well as application of acaricides, could influence prevalence variation. Argas persicus is a domestic and endophilic tick, typically adapted into the environments of poultry houses. As such, all developmental stages have been observed on hosts and in lodgings from several infested farms from the current study.
Morphological discrimination between A. persicus and other Argas species, specifically A. reflexus, which have been reported from some North African countries (Tunisia and Egypt; see Hoogstraal and Kohls 1960; Vermeil et al. 1996), remains difficult. Molecular characterization allows optimal identification and differentiation between A. persicus and A. reflexus. The present study provides the first molecular data regarding genetic characterization and phylogenetic analysis of A. persicus samples from Algeria. Additionally, the current study reports molecular characterization of A. persicus samples from China and phylogenetic relationships of this soft tick species originating from different regions worldwide. Genetic characterization of A. persicus has been reported in Africa (Egypt, Kenya and South Africa: Dabert et al. 1999; Mans et al. 2019), Europe (Romania and Italy: Chitimia et al. 2010; Pantaleoni et al. 2010), Asia (China, Iran, Kazakhstan and Pakistan: Feng et al. 2019; Sheng et al. 2019; Yavari et al. 2019; Chen et al. 2020; Sang et al. 2021; Zahid et al. 2021), the Americas (USA and Chile: Black et al. 1997; Norris et al. 1999; Muñoz-Leal et al. 2018), and Australia (Petney et al. 2004). Within A. persicus, two distinct clades were recovered, corresponding to A. persicus s.s. from Algeria and different countries worldwide (including some parts of China), and A. persicus s.l. from East China. Based mainly on 16S rRNA sequence data (Fig. 4), most Algerian samples showed close phylogenetic association together, likely related to the same sampling area of ticks where related tick generations have evolved through several life cycles from same hosts and environmental conditions. Conserved genetic sequences have been reported for A. persicus populations either from same area (as example in China) or from distant Iranian regions (Feng et al. 2019; Yavari et al. 2019). However, in some studies, A. persicus populations originating from two distant areas (e.g., Tongliao semi-humid region and Alxa semi-arid area or desert zone from China) or different countries (e.g., Australia, Egypt) exhibited very low genetic variation (intraspecific variation) (Petney et al. 2004; Feng et al. 2019). On the one hand, finding of the present study confirmed occurrence of A. persicus s.s. both in Algeria and China (two samples N°43 and 44 from Gansu). On the other hand, A. persicus s.l. from China in the current study and reference samples from different, but generally eastern Chinese regions (Tongliao area referred to accession number LC209197, Alxa to LC209198, and Xingtai City, Hebei Province to MT012684 and NC053794; see Feng et al. 2019; Chen et al. 2020), displayed a district clade from A. persicus s.s. from Algeria and other countries worldwide (including samples from China Wusu Xinjiang). These samples represent a divergent lineage of A. persicus that may prove to be a distinct species if other data, such as detailed morphology or breeding trials, support our findings. Our suggestion was supported by finding of Feng et al. (2019), which reported distinct polymorphisms in the 16S rRNA gene sequences and no close evolutionary phylogenetic distance between A. persicus s.s. from Wusu Xinjiang (KR297208) and the Chinese A. persicus lineage from Tongliao (LC209197) and Alxa (LC209198). Therefore, both lineages (A. persicus s.s. and A. persicus s.l. “East China”) occur in China, either in the same area (Gansu province) as our study showed or in distant areas. As such, these two lineages exhibit geographic overlap in central China approximately between Wusu and Gansu based on the presence of A. persicus s.s. in Gansu (samples N°43 and 44) and Wusu (KR297208), but lack of A. persicus s.s. toward the eastern parts (Figs. 4, 5, 6). This may be the result of historical peripatric divergence on the eastern periphery of the A. persicus population with dispersal back to the central China region over time, possibly by means of human-related movement of domestic fowl. Furthermore, a recent molecular study from Spain (Segovia and Guadalajara provinces, both in the interior of the Iberian Peninsula) have reported occurrence of Argas spp. genotype (16S rRNA; MW289073, MW289074) closely related to the Chinese lineage of A. persicus (Palomar et al. 2021). It seems that the geographical extent of this lineage is broader than its particular occurrence in China. Recently, Chen and Liu (2022) documented the distribution of A. persicus in the different parts of China, including Palearctic, Oriental, and Paleozoic–Oriental ecotone regions. This distribution would be better reconsidered since both lineages occur in China.
In conclusion, the present study reports for the first time molecular characterization and phylogenetic analysis of A. persicus infesting domestic birds from east of Algeria. Occurrence of A. persicus s.s. both in Algeria and China was confirmed. In addition, this study provides valuable molecular data on occurrence of distinct Chinese lineage of A. persicus. Exhaustive, large-scale studies are desirable in future to better understand ecology and distribution of this soft tick in the different climatic regions of Algeria, as well as its impact on poultry production and its role as vector of pathogens both of veterinary and medical importance. Furthermore, future works should be conducted on wide range samples of A. persicus from different areas in China to further investigate the geographic boundary lies between the two lineages and test if detailed morphology and biology of these tick populations supports different lineages, which likely may indicate distinct species.