Bacterial Microbiota Analysis Demonstrates That Tick Can Acquire Bacteria From Habitat and Host Blood Meal

Abstract

Exploring the bacterial microbiota is imperative to tick control since it has an important role in tick physiology and vector capacity. The life cycle of ticks consists of parasitic and non-parasitic stages, with a diversity of habitats and host blood meals. Whether and how these factors, such as tick developmental stages, tick organs, habitats and host blood meals affect tick bacterial microbiota is poorly elucidated. In the present study, we investigated the bacterial microbiotas of hard tick Haemaphysalis longicornis, their blood meals and habitats using 16S rRNA high-throughput sequencing. The bacterial richness and diversity in ticks varied depending on the tick developmental stage, feeding status and the tick organs. Results showed that fed ticks present a higher bacterial richness suggesting that ticks may acquire bacteria from blood meals. The significant overlap of the bacteriota of fed ticks and the host blood also support this possibility. Another possibility is that blood meals can stimulate the proliferation of certain bacteria. However, most shared bacteria cannot transmit throughout the tick life cycle, as they were not present in tick eggs. The most shared bacteria between ticks and habitats are genus of Staphylococcus, Pseudomonus, Enterobacter, Acinetobacer and Stenotrophomonas, some of them are also present in tick organ, suggesting that these environmental bacteria cannot be completely washed away and can be acquired by ticks. As tick reproductive organ, ovary showed the lowest bacterial richness and diversity compared to other organs. The predominant proportion of Coxiella in fed females and ovary further demonstrated that this genus is required for H. longicornis reproduction system. These findings further reveal that the bacterial composition of ticks is influenced by a variety of factors and will help in subsequent studies of the function of these bacteria.