Steidle Johannes L M, Steppuhn Anke, Ruther Joachim
Angewandte Zoologie/Okologie der Tiere, Institut für Biologie, Freie Universität Berlin, Haderslebener Str. 9, 12163 Berlin, Germany.
J Chem Ecol. 2003 Jan;29(1):131-43. doi: 10.1023/a:1021932731350.
In general, it is assumed that generalist natural enemies do not innately use specific cues for the location of their host or prey species. This hypothesis was tested using naïve females of the generalist parasitoid Lariophagus distinguendus Förster and two of its hosts, larvae of the lesser grain borer Rhyzopertha dominica (F.) and of the granary weevil Sitophilus granarius L., feeding in wheat grains. In a four-chamber olfactometer, female parasitoids were attracted to volatiles emanating from the feces of both host species. Chemical analysis of the volatiles from the feces of R. dominica revealed the presence of dominicalure 1 and 2, the species specific aggregation pheromones of R. dominica. The main compounds in the volatiles from feces of S. granarius were identified as chemicals related to mites that are associated with hosts of L. distinguendus. Because these mites are not specific for S. granarius but also co-occur with other hosts, the mite chemicals have to be considered as general cues. In bioassays, synthetic dominicalure was attractive to naïve L. distinguendus, explaining the attraction of feces volatiles from R. dominica. Synthetic mite chemicals and sitophilate, the aggregation pheromone of S. granarius, had no effect on naïve parasitoids. It remains to be determined which innate chemical cues from feces of S. granarius are used by L. distinguendus. In contrast to our initial hypothesis, the generalist L. distinguendus is innately using specific cues for foraging. Two ideas are provided to explain this result.
一般来说，人们认为广食性天敌不会天生利用特定线索来定位其寄主或猎物物种。本研究使用广食性寄生蜂区分拉瑞食蜂（Lariophagus distinguendus Förster）的未接触过相关信息的雌蜂及其两种寄主——在小麦粒中取食的谷蠹（Rhyzopertha dominica (F.)）幼虫和谷象（Sitophilus granarius L.），对这一假设进行了检验。在一个四室嗅觉仪中，雌性寄生蜂被两种寄主物种粪便散发的挥发物所吸引。对谷蠹粪便挥发物的化学分析显示存在谷蠹引诱剂1和2，这是谷蠹的物种特异性聚集信息素。谷象粪便挥发物中的主要化合物被鉴定为与螨类相关的化学物质，这些螨类与区分拉瑞食蜂的寄主有关。由于这些螨类并非谷象所特有，也与其他寄主共生，因此这些螨类化学物质必须被视为一般线索。在生物测定中，合成的谷蠹引诱剂对未接触过相关信息的区分拉瑞食蜂具有吸引力，这解释了谷蠹粪便挥发物的吸引力。合成的螨类化学物质和谷象聚集信息素谷象素对未接触过相关信息的寄生蜂没有影响。区分拉瑞食蜂利用谷象粪便中的哪些先天化学线索还有待确定。与我们最初的假设相反，广食性的区分拉瑞食蜂天生利用特定线索进行觅食。本文提供了两种观点来解释这一结果。
