Acarology Research Laboratory, Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia.
Plant Pathology Laboratory, Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia.
PLoS One. 2020 May 19;15(5):e0233389. doi: 10.1371/journal.pone.0233389. eCollection 2020.
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.
东方叶螨，Eutetranychus orientalis（Klein），是包括沙特阿拉伯（SA）在内的许多国家柑橘的主要害虫。据报道，该种的不同种群存在形态变异。在本研究中，评估了来自 SA 不同宿主和地区的 10 个东方叶螨种群的 40 种不同形态特征的表型变异。此外，还使用 ITS2-rDNA 序列确认了这些表型变异种群的身份。所有种群的形态均发生了变化，包括背毛的形状和长度、d1 和 e1 之间的条纹模式以及足的刚毛形态。对这些形态变异种群的 rDNA 序列分析产生了 10 种不同的沙特 ITS2 单倍型。表型和遗传变异与宿主植物的关系更为密切，而与地理分布关系不大。从 Phoenix dactylifera 采集的东方叶螨种群在表型上明显不同，遗传上也存在差异。从柑橘属植物采集的种群在表型和遗传上也比从非柑橘属植物采集的种群更为相似。从不同地区采集的 Ziziphus sp.、Morus sp. 和 Azadirecta indica 的种群聚在同一亚分支中。此外，从利雅得和欧拉的 Citrus reticulata 中分离出的沙特东方叶螨 ITS2 单倍型与从以色列的柑橘属植物中分离出的 ITS2 单倍型完全相同。结论是，栖息在不同宿主植物上的东方叶螨种群存在表型变异。在识别时应充分考虑种内的表型变异。
