Data from: Oviposition preference of cabbage white butterflies in the framework of costs and benefits of interspecific herbivore associations

When deciding where to oviposit, herbivorous insects consider: (i) the plant’s value as a food source, (ii) the risks of competing with con- and heterospecific herbivores, and (iii) the risks of parasitism and predation on the host plant. The presence of con- and/or heterospecific competitors would further affect the oviposition preference, because the preceding herbivores induce direct/indirect defences in plants against forthcoming herbivores, and thereby alter oviposition decisions. In previous studies, the abovementioned factors have not been studied in an integrative manner. We performed here a case study of this by assessing the oviposition preferences of a small white butterfly, Pieris rapae, for plants occupied by combinations of conspecific larvae, heterospecific larvae (Plutella xylostella), specialist parasitoids of Pi. rapae (Cotesia glomerata) and generalist predators (ants). We previously reported that the females showed equal preference for Pl. xylostella-infested and uninfested plants. Here, we showed that Pi. rapae females preferred uninfested plants to conspecific-infested ones, and Pl. xylostella-infested plants to Pi. rapae-infested ones. We discuss these oviposition preferences of Pi. rapae females in the framework of costs and benefits of interspecific herbivore associations from the above point of view.

植食性昆虫在抉择产卵位点时，需考量三类核心因素：(i) 植物作为食物源的价值；(ii) 与同种及异种植食者竞争的风险；(iii) 寄主植物面临的寄生与捕食风险。同种或异种竞争者的存在会进一步影响产卵偏好，因先期取食的植食者可诱导植物产生针对后续植食者的直接/间接防御反应，进而改变昆虫的产卵决策。过往研究尚未以整合视角对上述三类因素开展系统性探究。本研究以菜粉蝶（Pieris rapae）为研究对象开展案例研究，通过评估其对被以下组合侵染的植物的产卵偏好，完成了对上述因素的整合性分析：同种幼虫、异种幼虫（小菜蛾Plutella xylostella）、菜粉蝶专性寄生蜂（菜蛾盘绒茧蜂Cotesia glomerata）以及广食性捕食者（蚂蚁）。我们此前曾报道，菜粉蝶雌蝶对小菜蛾侵染植株与未侵染植株的产卵偏好无显著差异。本研究结果显示，菜粉蝶雌蝶更偏好未侵染植株而非同种幼虫侵染的植株，同时更偏好小菜蛾侵染的植株而非菜粉蝶自身幼虫侵染的植株。我们将基于上述视角，从种间植食者关联的成本-收益框架出发，对菜粉蝶雌蝶的上述产卵偏好展开讨论。