Mitochondrial and Nuclear DNA Analyses of Rhipicephalus microplus from Mizoram, Northeast India: Insights into Genetic Diversity and Endosymbiont

TL;DR

This study explores the genetic diversity and endosymbiont presence in Rhipicephalus microplus ticks from Mizoram, India, revealing new phylogenetic insights and regional population patterns.

Contribution

The first molecular analysis of R. microplus in Mizoram, revealing novel phylogenetic and endosymbiont data from a strategically important region.

Findings

R. microplus populations from India, Bangladesh, and Pakistan form a distinct matrilineal lineage within clade C.

24 COX1 haplotypes were identified globally, with only one found in India.

Coxiella-like endosymbionts were detected in 95% of the analyzed tick specimens.

Abstract

Background/Objectives: In this study, we conducted molecular identification of R.microplus and explored the genetic diversity of R. microplus for the first time in Mizoram, a Northeastern Hill (NEH) state of India bordering Myanmar. Methods: To assess genetic variation and evolutionary relationships, we employed phylogenetic analyses, genetic divergence metrics, and haplotype network construction based on mitochondrial (COX1 and 16S rDNA) and nuclear (ITS-2 and 18S rDNA) markers. Additionally, multivariate Principal Coordinate Analysis (PCoA) was used to visualize genetic differentiation among R. microplus populations. Results: Our analyses indicated that populations of R. microplus sensu lato from India, Bangladesh, and Pakistan form a closely related matrilineal lineage distinct from R. microplus sensu stricto, clustering within clade C of the COX1-based phylogeny. Globally, 24 COX1 haplotypes were recovered, with 1 haplotype identified in India. The Mizoram population exhibited a single 16S rDNA haplotype; however, intraspecific divergence was evident across India, with seven matrilineal haplotypes detected and nineteen globally. Further, five haplotypes were identified within R. microplus using the ITS-2 marker, while five haplotypes were observed within the Rhipicephalus genus using the 18S rDNA marker. Moreover, this study revealed the presence of Coxiella-like endosymbionts in 95% of the tick specimens analyzed. Conclusions: This study fills a critical knowledge gap by providing the first molecular documentation of tick diversity in Mizoram, a strategic region along the Indo–Myanmar border, and offers novel insights into the phylogeography and symbiotic associations of R. microplus and related tick taxa.

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