Hall David R, Farman Dudley I, Cross Jerry V, Pope Tom W, Ando Tetsu, Yamamoto Masanobu
Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent, UK.
J Chem Ecol. 2009 Feb;35(2):230-42. doi: 10.1007/s10886-009-9588-6. Epub 2009 Jan 24.
The raspberry cane midge, Resseliella theobaldi, is a widespread pest of cultivated red raspberry in Europe. Pheromone-baited traps could provide a much-needed, accurate means to monitor the pest. Volatiles collected separately from virgin female and male midges were analyzed by gas chromatography (GC) coupled to mass spectrometry (MS) to reveal four female-specific components. In analyses by GC coupled to electroantennographic (EAG) recording from the antennae of a male midge, at least three of these components elicited responses. Based on its GC retention indices and mass spectrum, we propose that the major component is 2-acetoxy-5-undecanone and confirm this by synthesis of the racemic compound in seven steps and 63% yield from 4-pentenoic acid. The three minor components were each present at approximately 30% of the major component and were identified as 2-undecanone, (S)-2-acetoxyundecane, and (S)-2-undecanol by comparison of GC retention times and mass spectra with those of synthetic standards. GC analyses of the female-produced volatiles on an enantioselective column showed that only one enantiomer of 2-acetoxy-5-undecanone was present, and this was found to be the S-enantiomer by hydrolytic kinetic resolution of an epoxide intermediate in the synthesis and also by enantioselective hydrolysis of the racemic acetate with a lipase enzyme. The two enantiomers were also separated by high-performance liquid chromatography on an enantioselective column for field tests. In two field trapping tests, (S)-2-acetoxy-5-undecanone was highly attractive to male R. theobaldi; the R-enantiomer was not attractive. The racemic compound was just as attractive as the S-enantiomer, and addition of the three minor components in racemic form at two different loads did not affect catches. The pheromone could be dispensed from both rubber septa and polyethylene vials for at least 1 month under field conditions, but the former was preferred as it gave more uniform release. 2-Acetoxy-5-undecanone belongs to a new group of pheromone structures in the Cecidomyiidae, most others being mono- or diesters.
悬钩子瘿蚊（Resseliella theobaldi）是欧洲栽培红树莓的一种广泛分布的害虫。信息素诱捕器可为监测这种害虫提供急需的准确方法。分别从未交尾的雌蚊和雄蚊收集的挥发物通过气相色谱（GC）与质谱（MS）联用进行分析，以揭示四种雌性特异性成分。在通过GC与来自雄蚊触角的电触角图（EAG）记录联用的分析中，这些成分中至少有三种引发了反应。根据其GC保留指数和质谱，我们提出主要成分是2-乙酰氧基-5-十一烷酮，并通过从4-戊烯酸经七步合成外消旋化合物并以63%的产率予以证实。三种次要成分各自的含量约为主成分的30%，通过将GC保留时间和质谱与合成标准品进行比较，鉴定为2-十一烷酮、（S）-2-乙酰氧基十一烷和（S）-2-十一醇。在对映选择性柱上对雌性产生的挥发物进行的GC分析表明，2-乙酰氧基-5-十一烷酮仅存在一种对映体，通过合成中环氧中间体的水解动力学拆分以及用脂肪酶对外消旋乙酸酯进行对映选择性水解，发现其为S-对映体。这两种对映体也通过在对映选择性柱上的高效液相色谱进行分离，用于田间试验。在两次田间诱捕试验中，（S）-2-乙酰氧基-5-十一烷酮对雄性悬钩子瘿蚊具有高度吸引力；R-对映体没有吸引力。外消旋化合物与S-对映体的吸引力相同，以两种不同载量添加外消旋形式的三种次要成分不影响捕获量。在田间条件下，信息素可从橡胶隔片和聚乙烯小瓶中释放至少1个月，但前者更受青睐，因为其释放更均匀。2-乙酰氧基-5-十一烷酮属于瘿蚊科中一类新的信息素结构，大多数其他信息素为单酯或二酯。
