Department of Entomology, Nanjing Agricultural University, Nanjing, People's Republic of China.
PLoS One. 2013 Apr 8;8(4):e60832. doi: 10.1371/journal.pone.0060832. Print 2013.
Host specialization is a ubiquitous character of phytophagous insects. The polyphagous population is usually composed of some subpopulations that can use only a few closely related plants. Cotton-melon aphids, Aphis gossypii Glover exhibited strong host specialization, and the cotton- and cucurbits-specialized biotypes had been clearly identified. However, the experimental work that addressed the roles of plant species in determining diet breadth of phytophagous insects is rare. In the present study, we took the artificial host transfer method to assess the role of two special plants, zucchini Cucurbita zucchini L. and cowpea Vigna unguiculata (Linn.) Walp, in regulating diet breadth of cotton- and cucurbits-specialized A. gossypii collected from cotton and cucumber fields and reared separately on the native host plant for ten years. The results showed that the cotton-specialized aphids did not directly use cucumber whereas the cucurbits-specialized did not use cotton regardless of the coexistence or separation of cotton and cucumber plants. Neither of the cotton- and cucurbits-specialized aphids could use capsicum Capsicum annuum, eggplant Solanum melongenahttp://en.wikipedia.org/wiki/Carolus_Linnaeus, tomato Solanum lycopersicum, maize Zea mayshttp://en.wikipedia.org/wiki/Carl_Linnaeus, and radish Raphanus sativus, however, both of them could use zucchini and cowpea. Moreover, the feeding experience on zucchini led the cotton-specialized aphids to use cucumber well and finally to be transformed into the cucurbits-specialized biotype. The short-term feeding experience on cowpea resulted in the diet breadth expansion of the cucurbits-specialized aphids to use cotton. On the other hand, the diet breadth expansion of the cucurbits- and cotton-specialized aphids was only realized by different species of plant. It concluded that the special host plant did induce the conversion of feeding habits in the cotton- and cucurbits-specialized aphids, and consequently broke the host specialization. The plant species is an underlying factor to determine the diet breadth of phytophagous insects.
昆虫的寄主专化性是普遍存在的特征。多食性种群通常由一些只能利用少数近缘植物的亚种群组成。棉蚜，Aphis gossypii Glover 表现出很强的寄主专化性，已经明确鉴定出棉花专化型和葫芦科专化型。然而，关于植物物种在决定植食性昆虫食性广度中的作用的实验工作却很少。在本研究中，我们采用人工寄主转移法，评估了两种特殊植物——西葫芦 Cucurbita zucchini L. 和豇豆 Vigna unguiculata（Linn.）Walp——在调节分别在棉花和黄瓜上连续饲养十年的来自棉花和黄瓜田的棉花专化型和葫芦科专化型 A. gossypii 食性广度中的作用。结果表明，棉花专化型蚜虫不直接利用黄瓜，而葫芦科专化型蚜虫无论棉花和黄瓜植物共存还是分离，都不利用棉花。棉花专化型和葫芦科专化型蚜虫都不能利用辣椒 Capsicum annuum、茄子 Solanum melongena、番茄 Solanum lycopersicum、玉米 Zea mays 和萝卜 Raphanus sativus，但它们都可以利用西葫芦和豇豆。此外，在西葫芦上的短期取食经验使棉花专化型蚜虫能够很好地利用黄瓜，最终转变为葫芦科专化型。在豇豆上的短期取食经验导致葫芦科专化型蚜虫的食性广度扩大，能够利用棉花。另一方面，棉花专化型和葫芦科专化型蚜虫的食性广度扩大仅通过不同的植物物种来实现。综上所述，特殊的寄主植物确实诱导了棉花专化型和葫芦科专化型蚜虫取食习性的转变，从而打破了寄主专化性。植物物种是决定植食性昆虫食性广度的一个潜在因素。
