Ixodes ricinus tick bacteriome alterations based on a climatically representative survey in Hungary

Abstract

Climate-sensitive disease vectors, such as ticks, respond to the environment with changes in their microbiome. These changes can affect the emergence or re-emergence of various vector-borne pathogens, such as the causative agent of Lyme borreliosis (LB) or tick-borne encephalitis. This aspect is particularly emphasized in light of climate change. The climatically representative assessment of microbiome differences in various developmental stages of the most common Central European tick species, Ixodes ricinus, deepens our understanding of the potential climatic factors behind microbial relative abundance and interaction changes. This knowledge can support the development of novel disease vector control strategies.

Keywords: Ixodes ricinus; bacteriome; climate; female; nymph.

Fig 1

Climate category spatial pattern and sampling points. The color of the sylvan areas is defined by the climatic categories based on GDD and precipitation over the period 2008–2017. The points are relatively homogeneous within Hungary geographically.

Fig 2

Richness and evenness of Ixodes ricinus bacteriome by sample groups. The number of observed species (richness) and the Inverse Simpson’s Index (evenness) as $\alpha$ -diversity metrics are presented in the form of a violin and box plot combination. These indices were calculated from 1,000 iterations of rarefied OTU tables with a sequencing depth of 158. The average over the iterations was taken for each sampling site. The violin plot shows the probability density of metrics, while the box plot marks the outliers, median, and IQR.

Fig 3

Core bacteriome composition of Ixodes ricinus samples. The relative abundance is plotted for the females and nymphs. Besides the bacterial genera of the core bacteriome, the environmental condition (GDD and precipitation) categories of sampling locations are also marked.

Fig 4

PCoA plots of $\beta$ -diversity estimated based on the core bacteriome of Ixodes ricinus samples.

Fig 5

Core bacteriome abundance fold changes by taxonomic ranks. The colors represent the Log2FC of the median abundances of the compared groups. Subfigure (a) shows the ratio of the abundances in females comparing nymphs as a reference. Figure (b) compares female samples from warmer areas to cooler ones. Figure (c) compares samples from drier areas to those from wetter areas among females. Comparisons of GDD groups in nymphs are shown in figure (d), while comparisons of precipitation groups are shown in figure (e).