Department of Entomology, Texas A & M University, College Station, TX 77843-2475, USA.
J Chem Ecol. 2011 Jun;37(6):629-39. doi: 10.1007/s10886-011-9960-1. Epub 2011 May 7.
Contact kairomones from the host mud dauber wasp Trypoxylon politum Say (Hymenoptera: Crabronidae) that mediate behavioral responses of its ectoparasitoid Melittobia digitata Dahms (Hymenoptera: Eulophidae) were investigated. Chemical residues from host by-products, the cocoon, and the meconium, induced arrestment behavior of macropterous female parasitoids, while those from the host stage attacked, i.e., the prepupa, did not. Melittobia digitata response to polar and apolar extracts of host by-products indicated kairomone(s) solubility mainly in hexane. GC and GC/MS analysis of cocoon and meconium apolar extracts revealed a mixture of linear carboxylic acids from C(6) to C(18), and both extracts contained almost identical compounds. When a reconstructed blend of host by-product carboxylic acids was tested, M. digitata females showed only a weak response, thus suggesting that other unidentified compounds present in small quantities also may be involved. Melittobia digitata's response to contact kairomones was innate and not affected by previous host exposure experience. Our results provide evidence of contact kairomone exploitation in the genus Melittobia. The ecological significance of these findings in the host selection process of M. digitata is discussed.
我们研究了宿主泥蜂 Trypoxylon politum Say（膜翅目：土蜂科）的接触信息素，这些信息素可以调节其外寄生蜂 Melittobia digitata Dahms（膜翅目：长尾小蜂科）的行为反应。宿主副产物、茧和胎粪中的化学残留物质诱导了雌性大翅寄生蜂的停止行为，而来自宿主攻击阶段（即预蛹）的化学残留物质则没有。Melittobia digitata 对宿主副产物的极性和非极性提取物的反应表明信息素（s）主要可溶于正己烷。茧和胎粪中非极性提取物的 GC 和 GC/MS 分析显示了一系列从 C(6) 到 C(18)的直链羧酸，并且两种提取物都含有几乎相同的化合物。当测试宿主副产物羧酸的重建混合物时，M. digitata 雌性只表现出微弱的反应，因此表明其他少量存在的未识别化合物也可能参与其中。Melittobia digitata 对接触信息素的反应是天生的，不受先前宿主暴露经验的影响。我们的研究结果为 Melittobia 属中接触信息素的利用提供了证据。讨论了这些发现对 M. digitata 宿主选择过程的生态意义。
