Trap crops are used for pulling the pest load from the main crops toward themselves. Here, we report a switching by a polyphagous pest, Spodoptera litura, from trap crop castor to main crop eggplant during its mid-larval development. In the eggplant–castor mixed field, adults oviposit exclusively on castor. However, 3rd and 4th instar castor-grown larvae migrate to eggplants. Host choice assays for adults and larvae conducted in the controlled environment and the nutritional indices of castor and eggplant-feeding larvae revealed that the natural enemies did not influence the host switch. The host switch was rather associated with larvae’s enhanced digestion and metabolism. It shortened the development time and increased the eclosion success on eggplant. Mother-selected castor is suitable for the early instars and eggplant is for the later instars, indicating that the host switching was not because of the mother’s erroneous host choice but has evolved as an advantageous behavior. S. litura’s ability to switch hosts in the same ontogenic phase and reduce the generation time can contribute to an additional generation within a cropping season and endanger the critical growth stage of fruiting. Our findings support the ‘mother knows the best’ concept and annex that the larvae can also possess the ability to know the best. Such ability in different ontogenic stages can be fundamental to the exceptional adaptability of species like S. litura.

圈套作物用于将有害生物负荷从主要作物拉向自身。在这里，我们报告了多食性害虫斜纹夜蛾的转换在幼虫中期发育期间，从诱集的农作物蓖麻到主要的农作物茄子。在茄子-蓖麻混合田中，成虫仅在蓖麻上产卵。然而，三龄和四龄蓖麻生长的幼虫迁移到茄子上。在受控环境中进行的成年和幼虫寄主选择试验以及蓖麻和茄子摄食幼虫的营养指数表明，天敌不会影响寄主的转换。寄主的转换与幼虫消化和新陈代谢的增强有关。缩短了开发时间，提高了茄子的成功套种成功率。母亲选择的蓖麻适合早期的幼虫，而茄子则适合晚期的幼虫，这表明宿主的切换不是由于母亲错误的宿主选择，而是一种有利的行为。小号。litura能够在同一个体发育阶段转换寄主，并缩短世代时间，这有助于在农作物季节内增加一世代，并危及结果的关键生长阶段。我们的发现支持“母亲知道最好”的概念，并认为幼虫也可以拥有了解最好的能力。在不同的个体发育阶段的这种能力可能是诸如斜纹夜蛾等物种异常适应性的基础。