Charaabi K, Carletto J, Chavigny P, Marrakchi M, Makni M, Vanlerberghe-Masutti F
Laboratoire de Génétique Moléculaire, Immunologie et Biotechnologie, Faculté des Sciences de Tunis, 2092 El Manar, Tunisia.
Bull Entomol Res. 2008 Aug;98(4):333-41. doi: 10.1017/S0007485307005585. Epub 2008 Feb 7.
The study of intraspecific variation with respect to host plant utilization in polyphagous insects is crucial for understanding evolutionary patterns of insect-plant interactions. Aphis gossypii (Glover) is a cosmopolitan and extremely polyphagous aphid species. If host plant species or families constitute selective regimes to these aphids, genetic differentiation and host associated adaptation may occur. In this study, we describe the genetic structure of A. gossypii collected in six localities in Tunisia on different vegetable crops, on citrus trees and on Hibiscus. The aim was to determine if the aphid populations are structured in relation to the host plants and if such differentiation is consistent among localities. The genetic variability of A. gossypii samples was examined at eight microsatellite loci. We identified only 11 multilocus genotypes among 559 individuals. Significant deviations from Hardy-Weinberg equilibrium, linkage disequilibria and absence of recombinant genotypes, confirmed that A. gossypii reproduces by continuous apomictic parthenogenesis. Genetic differentiation between localities was not significant, whereas a strong differentiation was observed between host plant families (0.175<FST<0.691). The great majority of aphids exhibited one of three predominant multilocus genotypes that were repeatedly and respectively associated to the three plant families, Cucurbitaceae, Solanaceae and Rutaceae, demonstrating host specialization in A. gossypii. These specialized genotypes were simultaneously found with other clones on Hibiscus, suggesting that this perennial host could act as a refuge plant between two vegetable crop seasons.
研究多食性昆虫在寄主植物利用方面的种内变异，对于理解昆虫与植物相互作用的进化模式至关重要。棉蚜（Aphis gossypii (Glover)）是一种世界性分布且多食性极强的蚜虫物种。如果寄主植物的种类或科属对这些蚜虫构成选择机制，那么可能会发生遗传分化和寄主相关适应性变化。在本研究中，我们描述了在突尼斯六个地点采集的棉蚜的遗传结构，这些地点的棉蚜分别取食不同的蔬菜作物、柑橘树和木槿。目的是确定蚜虫种群是否根据寄主植物形成结构，以及这种分化在不同地点之间是否一致。我们在八个微卫星位点上检测了棉蚜样本的遗传变异性。在559个个体中，我们仅鉴定出11种多位点基因型。与哈迪 - 温伯格平衡的显著偏差、连锁不平衡以及重组基因型的缺失，证实了棉蚜通过连续无融合孤雌生殖进行繁殖。不同地点之间的遗传分化不显著，而在寄主植物科属之间观察到强烈的分化（0.175 < FST < 0.691）。绝大多数蚜虫表现出三种主要多位点基因型中的一种，它们分别反复与三个植物科，即葫芦科（Cucurbitaceae）、茄科（Solanaceae）和芸香科（Rutaceae）相关联，这表明棉蚜存在寄主专一性。在木槿上同时发现了这些特化基因型与其他克隆，这表明这种多年生寄主植物可能在两个蔬菜作物季节之间起到避难所植物的作用。
