Mechanisms and specifictiy of sequestration in the genus Athalia

在十目锯蝇中，有几个物种的幼虫表现出一种特殊的现象，即“易出血”。对幼虫被膜的轻微机械损伤足以刺激在该部位释放血淋巴，这对许多拮抗剂起威慑作用。对于一些锯蝇物种来说，已经证明这种威慑原理与寄主植物的化学有关：幼虫吸收某些植物代谢物并将其隔离在它们的血淋巴中。然而，摄取机制尚不清楚，因为几种寄主植物的隔离代谢物是糖苷，通常在植物组织破坏后被糖苷酶迅速水解。该项目的主要目的是表征锯蝇属植物代谢产物吸收和转化的特异性和机制。对于蔷薇，将更详细地研究从十字花科寄主植物中吸收硫代葡萄糖苷。与其他以芸苔科和车前草科为食的Athalia物种的比较将阐明“易出血植物”中吸收机制的共同和衍生特征。不同的隔离代谢物作为防御捕食者的有效性将有助于了解适应价值。

Several species within the tenthredinid sawflies are well characterised by a specific phenomenon exhibited by the larvae, the ‚easy bleeding’. Slight mechanical damage of the larval integument is sufficient to provoke the release of haemolymph at that given spot, which acts deterrent on many antagonists. For a few sawfly species it has been shown that the deterrent principle is related to the host plant chemistry: larvae take up certain plant metabolites and sequester them in their haemolymph. The uptake mechanism is however unclear, as the sequestered metabolites of several host plants are glycosides that are usually rapidly hydrolysed by glycosidases after disruption of plant tissue. The main aim of the project is to characterise the specificity and mechanisms of the uptake and turn-over of sequestered plant metabolites in the sawfly genus Athalia. For A. rosae sequestration of glucosinolates from host plant species within the Brassicaceae will be studied in more detail. Comparisons with other Athalia species that feed on Brassicaceae and on Plantaginaceae will clarify common and derived features of sequestration mechanisms within the ‘easy bleeders’. The effectiveness of different sequestered metabolites as defence against predators will give insight in the adaptive values.