USDA-ARS, Yakima Agricultural Research Laboratory, Wapato, WA 98951, USA.
J Econ Entomol. 2010 Aug;103(4):1060-70. doi: 10.1603/ec10027.
The psyllid Trioza apicalis Förster (Hemiptera: Triozidae) is a serious pest of carrots, Daucus carota L., in Europe. Carrots exhibiting symptoms of psyllid damage were observed in commercial fields in southern Finland in 2008. Symptoms in affected plants included leaf curling, yellow and purple discoloration of leaves, stunted growth of shoots and roots, and proliferation of secondary roots. Mechanisms by which T. apicalis induces symptoms in plants are not understood, and no plant pathogens have yet been associated with this insect. Given recent association of liberibacter with several crops affected by psyllids, an investigation on whether this bacterium is associated with T. apicalis was conducted. Polymerase chain reaction (PCR) primer pairs OA2/OI2c and LsoF/OI2c, specific for 16S rRNA gene from "Candidatus Liberibacter solanacearum," generated amplicons of 1,168 bp and 1,173 bp, respectively, from DNA extracted from field-collected psyllids (61 and 36.6%, respectively), laboratory-reared psyllids (70 and 33.3%, respectively), field-collected petioles from symptomatic carrots (80 and 55%, respectively), and laboratory-grown carrots (100% for both primer pairs). In contrast, no PCR products were detected in DNA extracted from insect-free plants. The DNA sequences of amplicons of the genes encoding liberibacter 16S rRNA from psyllids and carrots were identical. DNA of the 16S rRNA gene sequences determined from carrots and psyllids were 99.9% identical to analogous sequences of "Ca. L. solanacearum" amplified from several solanaceous crops and the psyllid Bactericera cockerelli (Sulc), a vector of this bacterium. This is the first report of a plant pathogen associated with T. apicalis and the second known psyllid species associated with "Ca. L. solanacearum".
桃蚜小蜂（Hemiptera: Triozidae）是欧洲胡萝卜（Daucus carota L.）的一种严重害虫。2008 年，在芬兰南部的商业田间观察到受桃蚜小蜂危害的胡萝卜出现症状。受影响植物的症状包括叶片卷曲、叶片变黄和变紫、芽和根生长受阻以及次生根增多。桃蚜小蜂在植物中诱导症状的机制尚不清楚，也尚未发现与这种昆虫有关的任何植物病原体。鉴于最近与几种受桃蚜小蜂影响的作物有关的韧皮杆菌的关联，进行了一项调查，以确定这种细菌是否与桃蚜小蜂有关。聚合酶链反应（PCR）引物对 OA2/OI2c 和 LsoF/OI2c 分别针对“Candidatus Liberibacter solanacearum”的 16S rRNA 基因，从田间采集的桃蚜小蜂（分别为 61%和 36.6%）、实验室饲养的桃蚜小蜂（分别为 70%和 33.3%）、来自有症状胡萝卜的田间采集的叶柄（分别为 80%和 55%）和实验室种植的胡萝卜（两种引物对均为 100%）中提取的 DNA 中产生 1168 bp 和 1173 bp 的扩增子。相比之下，从无虫植物中提取的 DNA 中未检测到 PCR 产物。桃蚜小蜂和胡萝卜中编码韧皮杆菌 16S rRNA 的基因扩增子的 DNA 序列相同。从胡萝卜和桃蚜小蜂中确定的 16S rRNA 基因序列与从几种茄科作物和该细菌的载体烟粉虱（Bactericera cockerelli）（Sulc）扩增的“Ca. L. solanacearum”的类似序列完全相同。这是与桃蚜小蜂相关的植物病原体的首次报道，也是与“Ca. L. solanacearum”相关的第二种已知的桃蚜小蜂。
