Effects of temperature on bacterial microbiome composition in Ixodes scapularis ticks

Abstract

Ixodes scapularis , the blacklegged deer tick, is the principal vector of Lyme disease in North America. Environmental factors are known to influence regional and seasonal incidence of Lyme disease and possibly the endemicity of the disease to the northeastern and upper mid‐western regions of the United States. With a goal to understand the impact of environmental temperature on microbial communities within the tick, we investigated the bacterial microbiome of colony‐reared I. scapularis ticks statically incubated at different temperatures (4, 20, 30, and 37°C) at a constant humidity in a controlled laboratory setting by comparison of sequenced amplicons of the bacterial 16S V4 rRNA gene to that of the untreated baseline controls. The microbiomes of colony‐reared I. scapularis males were distinct than that of females, which were entirely dominated by Rickettsia . In silico removal of Rickettsia sequences from female data revealed the underlying bacterial community, which is consistent in complexity with those seen among male ticks. The bacterial community composition of these ticks changes upon incubation at 30°C for a week and 37°C for more than 5 days. Moreover, the male ticks incubated at 30 and 37°C exhibited significantly different bacterial diversity compared to the initial baseline microbiome, and the change in bacterial diversity was dependent upon duration of exposure. Rickettsia ‐free data revealed a significantly different bacterial diversity in female ticks incubated at 37°C compared to that of 4 and 20°C treatments. These results provide experimental evidence that environmental temperature can impact the tick bacterial microbiome in a laboratory setting.

Temporal patterns inIxodes ricinusmicrobial communities: an insight into tick-borne microbe interactions

“…Similarly, the mean Shannon diversity index (=2.1) is in the range of what it has been previously observed in the literature for Ixodes ticks [8,20,41,42]. However, these values are commonly known to fluctuate, mainly according to the tick stages, species or localization, and are therefore difficult to compare [5,8,10,12,16,[42][43][44][45][46]. Furthermore, the fact that not all these studies used negative controls to identify potential contaminating OTUs and remove them from their datasets calls for caution in attempts to draw conclusions about these differences, particularly when we know that these OTUs can represent more than 50% of sequences detected in tick samples [22].…”

First metagenomic report of <i>Borrelia americana</i> and <i>Borrelia carolinensis</i> in Poland – a preliminary study

“…TIBOLA (tick-borne lymphadenopathy) syndrome in people bitten by Dermacentor reticulatus (1 male, 5 females) infected with R. raoulti is well known. Thapa et al [27] confirmed Rickettsia spp. domination in the metagenomic analysis of I. scapularis: the majority were the endosymbiotic Rickettsia buchneri which was absent in the current research.…”

“…The mechanism of Dermacentor and Ixodes feeding has a significant impact on pathogen transfer. These ticks' feeding is long-lasting and results in a large intake of vertebrate's blood [18,26,27]. Endosymbionts are also transmitted during tick meal [14].…”

The scale affects our view on the identification and distribution of microbial communities in ticks

“…The hypothesis that these studies may have been biased by detecting contaminant bacteria, coming from both extraction and amplification steps should thus not be ruled out [68]. In any case, studies recurrently support the differences of the tick microbiota according to tick life stages [63,65,66,69,70].…”

“…As previously mentioned, over their life-cycle, ticks are likely to experience the influence of the temporal variation of multiple factors such as temperature, hydric stress and diapause. All these factors are known to probably influence tick activity and metabolism and might potentially affect their microbiome [70]. While studies on tick microbial community diversity, composition and role have considerably increased in the past years, many questions arise about the temporal dynamics of the tick microbiome.…”