Molecular and phenotypic variations in Eutetranychus orientalis (Klein) populations from Saudi Arabia.

Jawwad Hassan Mirza,Amgad A Saleh,Muhammad Kamran,Fahad Jaber Alatawi,J Francis Borgio

doi:10.1371/journal.pone.0233389

Abstract

The oriental red spider mite, Eutetranychus orientalis (Klein) is a major pest of citrus in many countries including Saudi Arabia (SA). The morphological variations among the different populations of E. orientalis were reported. In the present study, phenotypic variations based on 40 different morphological characteristics were evaluated in 10 E. orientalis populations collected from different hosts and regions of SA. Further, ITS2-rDNA sequences were used to confirm the identity of these phenotypically varying populations. Phenotypic variations in all populations were found in the shape and length of dorsal setae, striation pattern between setae d1 and e1, and leg chaetotaxy. The rDNA sequence analysis of these morphologically varying populations resulted in 10 different ITS2 Saudi haplotypes. The phenotypic and genetic variations were more related to the host plants rather than their geographic distribution. The E. orientalis population collected from Phoenix dactylifera was phenotypically distinct and genetically divergent. The populations collected from citrus species were also more phenotypically and genetically related to each other than to populations collected from non-citrus host plants. The haplotypes recovered from Ziziphus sp., Morus sp., and Azadirecta indica from different regions were grouped in the same sub-clade. Further, the ITS2 haplotypes of Saudi E. orientalis recovered from Citrus reticulata from Riyadh and Al Ula were 100% identical to the ITS2 haplotypes recovered from Citrus sp. from Israel. It is concluded that phenotypic variations exist among different populations of E. orientalis inhabiting different host plants. This species should be identified carefully by considering phenotypic intraspecific variations.

Highlights

The oriental red spider mite, Eutetranychus orientalis (Klein), is a major pest of many economical shrubs and fruit trees including Citrus sp. and Prunus sp
Most variations observed in E. orientalis, collected from seven different host plants in 10 locations representing 5 regions of Saudi Arabia (SA), were in the lengths and shapes of dorsal body setae especially dorso-central setae, striation pattern between setae d1 and e1, and the length of legs and the chaetotaxy of leg segments; femora and tibiae (Tables 2 and 3)
The NJ phylogenetic tree based on 22 internal transcribed spacer 2 (ITS2) sequences of E. orientalis haplotypes from different countries including those recovered in the present study showed that most haplotypes were generally clustered based on host plant association rather than geographic distribution. (Fig 3)

Summary

Introduction

The oriental red spider mite, Eutetranychus orientalis (Klein), is a major pest of many economical shrubs and fruit trees including Citrus sp. and Prunus sp. It was reported that the morphological and genetic variations in E. orientalis populations could be caused by either vast geographic distribution or polyphagous feeding behavior of the species [11,12,13,14]. DNA-based intra and interspecific variations have been used to identify spider mite species [10, 15] and resolve many other cryptic species [16, 17]. DNA barcoding using short DNA sequences such as ITS2 or mitochondrial Cytochrome Oxidase I (COI) regions is an effective tool to study intraspecific variations within and among different populations of a species [18,19,20,21]

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Discussion

Conclusion