Microbiota Community Structure and Interaction Networks within Dermacentor silvarum, Ixodes persulcatus, and Haemaphysalis concinna

SIMPLE SUMMARY: Ticks pose a threat to humans and animals. However, microbial interactions on ticks are underappreciated. Complex microbial interactions shape microbial communities. There is limited information about microbial interactions on ticks, including Dermacentor silvarum, Ixodes persulcatus, and Haemaphysalis concinna. This study evaluated the microbial community composition of these three species and the microbial interactions based on pairwise interactions. The results reveal that the bacterial richness and microbiota structures of the three tick species are significantly different, and the bacterial richness of all ticks decreased significantly after they became engorged. A substantial expansion of the list of bacterial interactions was observed in ticks. ABSTRACT: Ticks carry and transmit a variety of pathogens, which are very harmful to humans and animals. To characterize the microbial interactions in ticks, we analysed the microbiota of the hard ticks, Dermacentor silvarum, Ixodes persulcatus, and Haemaphysalis concinna, using 16S rRNA, showing that microbial interactions are underappreciated in terms of shaping arthropod microbiomes. The results show that the bacterial richness and microbiota structures of these three tick species had significant differences. Interestingly, the bacterial richness (Chao1 index) of all ticks decreased significantly after they became engorged. All the operational taxonomic units (OTUs) were assigned to 26 phyla, 67 classes, 159 orders, 279 families, and 627 genera. Microbial interactions in D. silvarum demonstrated more connections than in I. persulcatus and H. concinna. Bacteria with a high abundance were not important families in microbial interactions. Positive interactions of Bacteroidaceae and F_Solibacteraceae Subgroup 3 with other bacterial families were detected in all nine groups of ticks. This study provides an overview of the microbiota structure and interactions of three tick species and improves our understanding of the role of the microbiota in tick physiology and vector capacity, thus being conducive to providing basic data for the prevention of ticks and tick-borne diseases.