Mesostigmatid mites (Acari: Mesostigmata) at the domestic-wildlife interface: Poultry and passerine birds of central Argentina

Wild birds may be considered a possible source of parasitic mesostigmatid mites for poultry, but only few studies explored this hypothesis. In addition, there is very little information about the parasitic mites present in commercial poultry systems from southern South America. To contribute with data on parasitic mesostigmatid mites at the domestic-wildlife interface, we conducted a study in which samples were systematically collected from laying hens and wild birds (adults and nestlings), for two years at three commercial laying hen farms. The occurrence of mesostigmatid mites were compared among hosts. A proportion of the collected mites were morphologically identified to the species level, finding that host preference varied greatly depending on mite species: laying hens were only parasitized by Ornithonyssus sylviarum, wild bird nestlings were mostly parasitized by Ornithonyssus bursa, and in small proportion, by O. sylviarum, while adult passerines were parasitized by both Ornithonyssus species, and sporadically by Pellonyssus cf. reedi and Dermanyssus cf. triscutatus. In laying hens, there was intraand inter-annual variability in mite occurrence, but no consistent seasonal pattern, whereas in adult wild birds, mites showed the highest prevalence in spring and the lowest in summer. Not coinciding with this general pattern, the occurrence of O. bursa matched the reproductive activity of wild birds. A phylogenetic analysis based on a fragment of the 16S rRNA gene was carried out for a subsample of the mites collected, showing that the O. sylviarum mites present on adult wild birds and laying hens had the same haplotype (100% identity). Additionally, mites obtained from wild birds morphologically identified as O. bursa presented two distinctive haplotypes (89.8% identity), one phylogenetically related to O. sylviarum and the other to O. monteiroi. These findings show that in central Argentina commercial laying hens are parasitized mainly by O. sylviarum while wild birds are also hosts to other mite species. Adult wild passerines, especially house sparrows, may be a source of O. sylviarum for commercial poultry.