Ixodes ricinus nymphs prefer blood with Borrelia infection and low corticosteroid concentration

Ticks play a significant role in the transmission of various pathogens, impacting both human and animal health. Understanding the factors influencing tick feeding preferences is crucial for mitigating the risk of tick-borne diseases. This study investigates the blood preference of Ixodes ricinus nymphs, focusing on host species, stress hormone levels (glucocorticoids), and the presence of Borrelia burgdorferi bacteria. Three series of in vitro experiments were conducted. The setup involved placing individual blood drops (15 {micro}l) on filter paper over a 37{degrees}C plate. Ticks were placed in the center, and their movements were tracked for two minutes to record preferences. The first experiment evaluated the ticks preference for blood from different hosts (mouse, bird, sheep). The second experiment explored the role of stress hormones by assessing the ticks response to blood with varying levels of supplemented cortisol and corticosterone (0, 10, 100 and 1000 ng/ml). The third experiment examined the potential influence of Borrelia infection, combined with elevated stress hormone levels, on blood preference. Our results show that I. ricinus nymphs show a significant preference for blood without added glucocorticoids and, in mice, blood with Borrelia infection. No clear preference for a specific host species was observed. These findings provide valuable insights into the complex interactions between ticks, blood characteristics, and Borrelia infection status, highlighting the potential importance of host physiological state in tick host selection. Future studies should explore the mechanisms behind these preferences, which could lead to the development of new methods to control the spread of tick-borne diseases. HIGHLIGHTSO_LIIn vitro experiments with nymphs can reveal insights into their blood preferences C_LIO_LITicks displayed no difference in preference towards bird, mouse, or sheep blood C_LIO_LITicks prefer blood with baseline stress levels over increased stress levels C_LIO_LIMouse blood infected with Borrelia burgdorferi was preferred by ticks C_LI