Department of Chemical Ecology, Bielefeld University, Universitätsstr. 25, 33615, Bielefeld, Germany.
J Chem Ecol. 2010 Feb;36(2):148-57. doi: 10.1007/s10886-010-9740-3. Epub 2010 Feb 2.
In this study, the larval sequestration abilities and defense effectiveness of four sawfly species of the genus Athalia (Hymenoptera: Tenthredinidae) that feed as larvae either on members of the Brassicaceae or Plantaginaceae were investigated. Brassicaceae are characterized by glucosinolates (GLSs), whereas Plantaginaceae contain iridoid glucosides (IGs) as characteristic secondary compounds. Athalia rosae and A. liberta feed on members of the Brassicaceae. Larvae of A. rosae sequester aromatic and aliphatic GLSs of Sinapis alba in their hemolymph, as shown previously, but no indolic GLSs; A. liberta larvae with a narrower host range sequester aliphatic as well as indolic GLSs from their host plant Alliaria petiolata. Larvae of A. circularis and A. cordata are specialized on members of the Plantaginaceae. Athalia circularis utilizes mainly Veronica beccabunga as host plant, whereas A. cordata feeds additionally on Plantago lanceolata. Both sawfly species sequester the IGs aucubin and catalpol. In V. beccabunga, catalpol esters and carboxylated IGs also occur. The high catalpol concentrations in hemolymph of A. circularis can only be explained by a metabolization of catalpol esters and subsequent uptake of the resulting catalpol. The carboxylated IGs of the plant are excreted. The IG-sequestering sawfly species are able to accumulate much higher glucoside concentrations in their hemolymph than the GLS-sequestering species, and the concentration of IGs in hemolymph increases constantly during larval development. The defensive effectiveness of hemolymph that contains GLSs or IGs and of the respective glucosides was tested in feeding-bioassays against a potential predator, the ant Myrmica rubra (Hymenoptera: Formicidae). Hemolymph of IG-sequestering cryptic A. cordata larvae has a higher deterrence potential than hemolymph of the GLS-sequestering conspicuous A. rosae larvae. The results show that glucoside sequestration is widespread in the genus Athalia, but that the specific glucoside uptake can result in different defense effectiveness against a predator species.
在这项研究中，研究了四种白杨（膜翅目：叶蜂科）幼虫的幼虫隔离能力和防御效果，这些幼虫要么以十字花科成员为食，要么以车前科成员为食。十字花科的特征是含硫葡萄糖苷（GLS），而车前科含有裂环烯醚萜苷（IGs）作为特征次生化合物。Athalia rosae 和 A. liberta 以十字花科成员为食。如先前所示，A. rosae 幼虫在其血液中隔离出白芥中的芳香族和脂肪族 GLS，但不隔离吲哚 GLS；A. liberta 幼虫的宿主范围较窄，从其宿主植物 Alliaria petiolata 中隔离出脂肪族和吲哚 GLS。A. circularis 和 A. cordata 的幼虫专门以车前科成员为食。A. circularis 主要利用 Veronica beccabunga 作为宿主植物，而 A. cordata 则另外以 Plantago lanceolata 为食。这两个叶蜂物种都隔离了 IGs 毛蕊花糖苷和梓醇。在 V. beccabunga 中，梓醇酯和羧化 IGs 也存在。A. circularis 血液中高浓度的梓醇只能通过梓醇酯的代谢和随后摄取产生的梓醇来解释。植物中的羧化 IGs 被排泄掉。IG 隔离的叶蜂物种能够在其血液中积累比 GLS 隔离的物种高得多的糖苷浓度，并且在幼虫发育过程中血液中 IG 浓度不断增加。在喂食生物测定中，测试了含有 GLS 或 IGs 及其相应糖苷的血液的防御效果，以对抗潜在的捕食者，红蚁（膜翅目：蚁科）。IG 隔离的隐蔽 A. cordata 幼虫的血液比 GLS 隔离的明显 A. rosae 幼虫的血液具有更高的驱避潜力。结果表明，糖苷隔离在白杨属中很普遍，但特定的糖苷摄取可能导致对捕食者物种的不同防御效果。
