As insects feed, stable isotopes from their diets are assimilated into their tissues. Stable isotopes provide a method to determine what insects are feeding on, and in some cases, where the insects have been feeding. One method for evaluating what adult holometabolous insects fed on as larvae, is to sample tissues from the integument of the adult. The integument should have isotopic signatures that reflect the diet of the larvae, and these inert tissues should be less influenced by adult feeding compared to other tissues. The objective of our research was to examine how isotopic signatures of nitrogen in various tissues of adult Popillia japonica (Newman) (Coleoptera: Scarabaeidae) beetles would be influenced by adults feeding on ¹⁵N-enriched plant material. We collected adults from emergences cages at unenriched grasses and fed them for 0, 2, 5, or 10 days with grape plants fertilized with isotopically enriched or unenriched potassium nitrate. The δ¹⁵N signature of elytra and soft tissues both increased over time when fed enriched plant material. The δ¹⁵N signatures of soft tissues were higher than that of the elytra over time. Adult beetles fed highly enriched plant material displayed increased δ¹⁵N signatures over time of tissues generally considered metabolically inactive, which suggests that adult feeding does contribute to the isotopic signatures of elytra tissue. The difference between the δ¹⁵N signatures of soft tissues and elytra demonstrates a lower turnover rate in the elytra and highlights the fact that diet does contribute to the signature of elytra.

中文翻译：

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成虫喂养对白杨不同组织δ15N特征的影响

当昆虫进食时，它们饮食中的稳定同位素被吸收到它们的组织中。稳定同位素提供了一种方法来确定昆虫以什么为食，以及在某些情况下，昆虫在何处觅食。评估成年全代谢昆虫作为幼虫进食的一种方法是从成虫的外皮中取样组织。外皮应具有反映幼虫饮食的同位素特征，与其他组织相比，这些惰性组织应较少受成虫喂养的影响。我们研究的目的是检查成年Popillia japonica (Newman) (Coleoptera: Scarabaeidae) 甲虫的各种组织中氮的同位素特征如何受到以¹⁵岁为食的成年甲虫的影响。富含氮的植物材料。我们从未浓缩草的出苗笼中收集成虫，并用富含同位素或未浓缩硝酸钾的葡萄植株喂养它们 0、2、5 或 10 天。当饲喂富含植物材料时，鞘翅和软组织的 δ ¹⁵ N 特征均随时间增加。随着时间的推移，软组织的 δ ¹⁵ N 特征高于鞘翅。喂养高度富集的植物材料的成年甲虫随着时间的推移显示出增加的 δ ¹⁵ N 特征，通常被认为是代谢不活跃的组织，这表明成年甲虫确实有助于鞘翅组织的同位素特征。δ ¹⁵之间的差异软组织和鞘翅的 N 特征表明鞘翅的周转率较低，并强调了饮食确实有助于鞘翅特征的事实。