The behavioral response of the larval parasitoid Spintherus dubius (Hymenoptera: Pteromalidae) to volatile compounds derived from its Apion weevil hosts was investigated in two-choice bioassays. Odor source candidates were the larval and adult stages of weevils, clover flowers, and feces from adult weevils. Despite S. dubius being a larval parasitoid, the odor of weevil larvae isolated from the clover flowers was not attractive to female parasitoids. Surprisingly, S. dubius females were instead attracted by the odor from the feces of adult weevils. The female parasitoids were similarly attracted to the feces produced by the two main hosts, the red clover weevil (A. trifolii) and the white clover weevil (A. fulvipes). Chemical analysis of the volatile composition of feces produced by the two hosts revealed qualitatively similar odor profiles, correlating with the observed attraction by the parasitoid towards both odor sources. Some of the identified volatile compounds are commonly present in clover plant headspace fractions and may function as a kairomone to facilitate orientation by S. dubius to Apion-infested clover flowers. Larval and adult weevils were not attractive for parasitoid females, whereas, for the white clover weevil-plant association, infested flowers were highly attractive. These data show the use by the clover weevil parasitoid of an alternative source of olfactory information for locating its host.

中文翻译：

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幼虫寄生蜂 Spintherus dubius（膜翅目：Pteromalidae）对成年 Apion 象鼻虫宿主粪便挥发物的吸引力

在两种选择的生物测定中研究了幼虫寄生蜂 Spintherus dubius（膜翅目：Pteromalidae）对源自其 Apion 象鼻虫宿主的挥发性化合物的行为反应。气味来源候选者是象鼻虫、三叶草花和成年象鼻虫的粪便的幼虫和成虫阶段。尽管 S. dubius 是幼虫寄生蜂，但从三叶草花中分离出的象鼻虫幼虫的气味对雌性寄生蜂没有吸引力。令人惊讶的是，S. dubius 雌性反而被成年象鼻虫粪便的气味所吸引。雌性寄生蜂同样被两种主要宿主产生的粪便所吸引，红三叶草象鼻虫 (A. trifolii) 和白三叶草象鼻虫 (A. fulvipes)。对两种宿主产生的粪便的挥发性成分进行化学分析，发现它们具有定性相似的气味特征，与观察到的寄生蜂对两种气味来源的吸引力相关。一些已鉴定的挥发性化合物通常存在于三叶草植物的顶部空间部分中，并且可能作为一种促进 S. dubius 定向到受 Apion 感染的三叶草花的 kairomone。幼虫和成年象鼻虫对寄生雌性没有吸引力，而对于白三叶草象鼻虫-植物协会来说，受侵染的花朵极具吸引力。这些数据显示了三叶草象鼻虫使用另一种嗅觉信息来源来定位宿主。对受 Apion 感染的三叶草花表示怀疑。幼虫和成年象鼻虫对寄生雌性没有吸引力，而对于白三叶草象鼻虫-植物协会来说，受侵染的花朵极具吸引力。这些数据显示了三叶草象鼻虫使用另一种嗅觉信息来源来定位宿主。对受 Apion 感染的三叶草花表示怀疑。幼虫和成年象鼻虫对寄生雌性没有吸引力，而对于白三叶草象鼻虫-植物协会来说，受侵染的花朵极具吸引力。这些数据表明三叶草象鼻虫使用另一种嗅觉信息来源来定位宿主。