Environmental variation experienced by a single genotype can induce phenotypic plasticity in various traits, such as behavioural, physiological and developmental characteristics. It can occur within the lifetime of an individual through within-generation phenotypic plasticity (WGP) or vertically across generations through transgenerational phenotypic plasticity (TGP). However, knowledge about TGP and the co-occurrence of WGP and TGP is still limited. In insect host-plant selection, the ability to alter phenotypic traits through WGP is well documented while the importance of TGP and the possible co-occurrence between the two is largely unknown. Host-plant selection of both larvae and adults of the polyphagous moth Spodoptera littoralis can be modified by previous experience through WGP. Thus, the aim of this study was to investigate if parental host-plant experience can influence host-plant choice behaviour and performance of S. littoralis offspring through TGP. For this, we tested effects of rearing parents on different host plants on the offspring’s first instar larval migration and host plant choice, larval development and adult oviposition. A transgenerational effect on larval development was found, with increased pupal weight on a matching host-plant diet to that of the parent, when larvae were reared on cotton (good larval host plant) while no such effect was found on maize (poor larval host plant). These findings indicate that TGP of S. littoralis progeny development traits may only occur under favourable conditions. Parental diet did not affect larval host plant choice or migration. Furthermore, no effect of parental diet was found on offspring oviposition behaviour, indicating that adult female host-plant selection is governed by innate preference hierarchy and WGP, rather than TGP. Thus, parental diet may influence offspring performance but not behaviour, indicating that WGP is most important for host-plant selection behaviours in S. littoralis, but TGP can affect progeny development. If so, the importance of different types of plasticity may vary among traits of S. littoralis associated with host plant utilisation.

中文翻译：

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植物诱导的跨代可塑性影响性能但不影响多食性蛾的偏好

单一基因型所经历的环境变异可以诱导各种性状的表型可塑性，例如行为、生理和发育特征。它可以通过代内表型可塑性 (WGP) 在个体的一生中发生，也可以通过跨代表型可塑性 (TGP) 垂直跨代发生。然而，关于 TGP 以及 WGP 和 TGP 共现的知识仍然有限。在昆虫宿主 - 植物选择中，通过 WGP 改变表型性状的能力已得到充分证明，而 TGP 的重要性和两者之间可能同时发生的情况在很大程度上是未知的。可以通过 WGP 以前的经验修改多食性蛾 Spodoptera littoralis 幼虫和成虫的宿主植物选择。因此，本研究的目的是调查亲本寄主植物经验是否可以通过 TGP 影响 S. littoralis 后代的寄主植物选择行为和表现。为此，我们测试了在不同寄主植物上饲养父母对后代第一龄幼虫迁移和寄主植物选择、幼虫发育和成虫产卵的影响。发现了对幼虫发育的跨代影响，当幼虫在棉花上饲养时（良好的幼虫宿主植物），在与亲本相匹配的寄主植物饮食上蛹重量增加，而在玉米上没有发现这种影响（差的幼虫寄主）植物）。这些发现表明 S. littoralis 后代发育性状的 TGP 可能仅在有利条件下发生。亲本饮食不影响幼虫寄主植物的选择或迁移。此外，没有发现亲本饮食对后代产卵行为的影响，表明成年雌性寄主植物选择受先天偏好等级和 WGP 控制，而不是 TGP。因此，父母的饮食可能会影响后代的表现而不是行为，这表明 WGP 对 S. littoralis 的寄主植物选择行为最重要，但 TGP 可以影响后代发育。如果是这样，不同类型的可塑性的重要性可能因与宿主植物利用相关的 S. littoralis 性状而异。但 TGP 会影响后代发育。如果是这样，不同类型的可塑性的重要性可能因与宿主植物利用相关的 S. littoralis 性状而异。但 TGP 会影响后代发育。如果是这样，不同类型的可塑性的重要性可能因与宿主植物利用相关的 S. littoralis 性状而异。