The diamondback moth (DBM), Plutella xylostella, is an oligophagous pest of cruciferous crops worldwide. Host plants of the DBM possess epicuticular wax, but thick wax is unfavorable to the selection of oviposition sites for female DBMs. How the DBM responds to host plant wax regarding oviposition site selection is largely unknown. The glucosinolates and wax levels in the cotyledons and true leaves of Chinese kale are different, which makes this plant an ideal host for exploring the oviposition behavior of the DBM. We found that although the true leaves contained more glucosinolates and waxy powder than cotyledons of healthy Chinese kale, DBM females preferred to lay eggs on the cotyledons over true leaves. However, the number of eggs laid on true leaves increased significantly when the waxy powder was artificially removed. Furthermore, the hatched larvae greatly preferred to feed and performed better on true leaves. In light of the current results, we propose that DBM females are hindered from laying eggs on the true leaves of Chinese kale by the outer layer of leaf wax powder. However, DBM females and larvae can adapt to the waxy host plant through adaptations: i.e., DBM females first lay eggs on the cotyledons where less wax exists, the hatched larvae then crawl to and spin silk nets on true leaves; the silk nets help subsequent DBM females overcome the obstacle of the wax and oviposit successfully on true leaves. These findings highlight new insights into plant–insect interactions.

小菜蛾（DBM），小菜蛾，是全世界十字花科作物的一种少食性害虫。DBM的寄主植物具有表皮蜡，但是厚蜡不利于雌性DBM的产卵部位的选择。关于产卵位的选择，DBM如何响应宿主植物蜡。芥蓝子叶和真叶中的芥子油苷和蜡含量不同，这使得该植物成为探索DBM产卵行为的理想宿主。我们发现，尽管真叶比健康芥蓝的子叶含有更多的芥子油苷和蜡状粉末，但DBM雌性更喜欢在子叶上产卵，而不是真叶。然而，当人为去除蜡状粉末时，在真叶上产卵的数量显着增加。此外，孵化的幼虫非常喜欢采食，并且在真叶上表现更好。根据目前的结果，我们建议叶蜡粉的外层阻止DBM雌性在芥蓝的真叶上产卵。但是，DBM雌虫和幼虫可以通过适应来适应蜡质寄主植物：例如，DBM雌虫首先在子叶上产卵，那里子蜡较少，孵化的幼虫然后爬到真叶上并在真叶上纺丝。蚕丝网帮助随后的DBM雌性克服蜡的障碍并成功地在真叶上产卵。这些发现突出了对植物与昆虫相互作用的新见解。DBM雌虫和幼虫可以通过适应来适应蜡质寄主植物：例如，DBM雌虫首先在子叶上产卵，而蜡子较少，孵出的幼虫然后爬到真叶上并在真叶上纺丝。蚕丝网帮助随后的DBM雌性克服蜡的障碍并成功地在真叶上产卵。这些发现突出了对植物与昆虫相互作用的新见解。DBM雌虫和幼虫可以通过适应来适应蜡质寄主植物：例如，DBM雌虫首先在子叶上产卵，而蜡子较少，孵出的幼虫然后爬到真叶上并在真叶上纺丝。蚕丝网帮助随后的DBM雌性克服蜡的障碍并成功地在真叶上产卵。这些发现突出了对植物与昆虫相互作用的新见解。