The relationship between female oviposition preference and offspring performance has been a question of special interest in the study of host plant selection by phytophagous insects. The Preference–Performance Hypothesis (PPH) is one of the main hypotheses proposed to explain this relationship, stating that females should preferentially lay eggs on plants providing the best larval development. The PPH has been extensively tested on aboveground insects but its application to species with belowground larvae is still mostly unknown. In this study, the PPH was quantitatively tested in an above-belowground insect, the cabbage root fly Delia radicum. Female oviposition preference and larval performance were estimated on three brassicaceous species (Brassica oleracea, Brassica rapa, and Sinapis alba) as well as between four cultivars of B. rapa and four cultivars of S. alba. Larval performance was estimated through their survival and through three life-history traits (LHT) of emerging adults. The PPH was supported at the intraspecific scale but only in B. rapa and for some, but not all, of the life-history traits. No support for the PPH was found in S. alba as well as at the interspecific scale. This study pleads for the integration of insects with both above‐ and belowground life stages in the preference–performance debate. Moreover, it raises the importance of measuring several variables to estimate larval performance and to test the PPH quantitatively, both at the plant intraspecific and interspecific scales, before drawing general conclusions.

雌性产卵偏好与后代表现之间的关系一直是植食性昆虫选择寄主植物研究中特别感兴趣的问题。偏好性能假设 (PPH) 是为解释这种关系而提出的主要假设之一，指出雌性应优先在提供最佳幼虫发育的植物上产卵。PPH 已经在地上昆虫上进行了广泛的测试，但它在地下幼虫物种中的应用仍然是未知的。在这项研究中，在地上地下昆虫白菜根蝇Delia radicum 中定量测试了 PPH 。对三种芸苔属植物（Brassica oleracea ,Brassica rapa和Sinapis alba ) 以及B. rapa 的四个品种和S. alba 的四个品种之间。幼虫的表现是通过它们的存活率和新兴成虫的三个生活史特征 (LHT) 来估计的。PPH 在种内规模上得到支持，但仅在B. rapa和一些（但不是全部）生活史特征中得到支持。在S. alba 中没有发现对 PPH 的支持以及在种间尺度上。这项研究呼吁在偏好 - 表现辩论中将昆虫与地上和地下生命阶段结合起来。此外，它提出了在得出一般结论之前测量几个变量以估计幼虫性能和定量测试 PPH 的重要性，包括植物种内和种间尺度。