Carotenoids play multiple roles in insects, including coloration and protection. Most insects can obtain carotenoids only from their diet. Therefore, carotenoids are proposed to reflect trophic chains and lifestyles of insects. We investigated the mini-ecosystem of a gall on a hawkweed Hieracium × robustum induced by the gall wasp Aulacidea hieracii (Hymenoptera: Cynipidae) that is attacked by parasitoid wasp Eurytoma cynipsea (Hymenoptera: Eurytomidae). The parasitoid larvae consume the gall wasp larvae that consume the gall tissues. We employed resonance Raman spectroscopy to trace the fate of carotenoids in living larvae and pupae of these insects. We showed that carotenoid composition in the parasitoid closely corresponds to that of its diet—the gall wasp. On the contrary, carotenoid composition in the gall wasp was independent of that in the gall tissues, and the carotenoid concentration increases as non-feeding larvae mature. Thus, A. hieracii is suggested as a candidate among insects to have the ability to synthesize and modify carotenoids. Our findings give rise to the question of the relevance of using carotenoids as markers of trophic flow in the gall community.

类胡萝卜素在昆虫中发挥多种作用，包括着色和保护。大多数昆虫只能从饮食中获取类胡萝卜素。因此，类胡萝卜素被认为可以反映昆虫的营养链和生活方式。我们研究了由寄生蜂Eurytoma cynipsea（膜翅目：Eurytomidae）攻击的瘿蜂Aulacidea hieracii （膜翅目：Cynipidae）诱导的山楂属Hieracium × robustum上的瘿微型生态系统。寄生蜂幼虫以瘿蜂幼虫为食，瘿蜂幼虫则以瘿组织为食。我们利用共振拉曼光谱来追踪这些昆虫活体幼虫和蛹中类胡萝卜素的命运。我们发现寄生蜂中的类胡萝卜素成分与其食物——瘿蜂的成分密切相关。相反，瘿蜂中的类胡萝卜素成分与瘿组织中的成分无关，并且类胡萝卜素浓度随着非摄食幼虫的成熟而增加。因此，A. hieracii被认为是昆虫中具有合成和修饰类胡萝卜素能力的候选者。我们的研究结果提出了使用类胡萝卜素作为胆菌群落营养流标记物的相关性的问题。