Kleinschmidt Birgit, Kölsch Gregor
Zoological Institute, Molecular Evolutionary Biology, University of Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany.
Insects. 2011 Dec 9;2(4):540-54. doi: 10.3390/insects2040540.
The present paper reviews the biology of reed beetles (Donaciinae), presents experimental data on the role of specific symbiotic bacteria, and describes a molecular method for the detection of those bacteria. Reed beetles are herbivores living on wetland plants, each species being mono- or oligo-phagous. They lay their eggs on the host plant and the larvae live underwater in the sediment attached to its roots. The larvae pupate there in a water-tight cocoon, which they build using a secretion that is produced by symbiotic bacteria. The bacteria are located in four blind sacs at the foregut of the larvae; in (female) adults they colonize two out of the six Malpighian tubules. Tetracycline treatment of larvae reduced their pupation rate, although the bacteria could not be fully eliminated. When the small amount of bacterial mass attached to eggs was experimentally removed before hatching, symbiont free larvae resulted, showing the external transmission of the bacteria to the offspring. Specific primers were designed to detect the bacteria, and to confirm their absence in manipulated larvae. The pupation underwater enabled the reed beetles to permanently colonize the wetlands and to diversify in this habitat underexploited by herbivorous insects (adaptive radiation).
本文综述了芦苇甲虫（Donaciinae）的生物学特性，展示了关于特定共生细菌作用的实验数据，并描述了一种检测这些细菌的分子方法。芦苇甲虫是食草动物，以湿地植物为食，每个物种都是单食性或寡食性的。它们在寄主植物上产卵，幼虫生活在水下附着于植物根部的沉积物中。幼虫在那里用共生细菌产生的分泌物构建一个防水茧进行化蛹。这些细菌位于幼虫前肠的四个盲囊中；在（雌性）成虫中，它们定殖在六个马氏管中的两个。用四环素处理幼虫会降低其化蛹率，尽管细菌不能被完全消除。当在孵化前通过实验去除附着在卵上的少量细菌团时，就会产生无共生体的幼虫，这表明细菌通过外部途径传递给后代。设计了特异性引物来检测这些细菌，并确认在经过处理的幼虫中不存在这些细菌。在水下化蛹使芦苇甲虫能够长期定殖在湿地，并在这个未被食草昆虫充分利用的栖息地实现多样化（适应性辐射）。
