Precise identification of different stages of a tick,Ixodes granulatus Supino,1897(Acari:Ixodidae)

摘要

Objective: To identify different stages of Ixodes granulatus(I. granulatus) based on morphological characters prior to molecular identification which is significant for confirming and identifying the nymphal stages of I. granulatus.Methods: A total of 14 individuals of adult, engorged and nymphal ticks collected from three different localities were examined morphologically using taxonomic keys, followed by PCR using cytochrome oxidase subunit I(COI). Clustering analysis based on COI sequences was carried out by constructing neighbor-joining and maximum parsimony tree to clarify the genetic variation and diversity of local I. granulatus.Results: Based on external morphological characterizations, nine individuals(64.3%)were successfully identified as I. granulatus, while five individuals were recognized only as Ixodes sp. due to lack of morphological characters visible and development during that stage. Molecular analysis of local I. granulatus using COI gene revealed 93%–94% sequence homology from available sequence in Gen Bank and was in concordance with the morphological identification. Furthermore, a low intraspecific variation was observed among the species of I. granulatus collected from different localities(0%–3.7%).Conclusions: These findings demonstrated for the first time the establishment of COI gene for identifying I. granulatus nymphal tick which is of paramount importance to the control of potential tick-borne infections in Malaysia. Moreover, this study provides evidence that a combination of morphology and molecular data was corroborated as an accurate tool for tick identification.