Data from: Preference for outbred host plants and positive effects of inbreeding on egg survival in a specialist herbivore

Inbreeding can profoundly affect the interactions of plants with herbivores as well as with the natural enemies of the herbivores. We studied how plant inbreeding affects herbivore oviposition preference, and whether inbreeding of both plants and herbivores alter the probability of predation or parasitism of herbivore eggs. In a laboratory preference test with the specialist herbivore moth Abrostola asclepiadis and inbred and outbred Vincetoxicum hirundinaria plants, we discovered that herbivores preferred to oviposit on outbred plants. A field experiment with inbred and outbred plants that bore inbred or outbred herbivore eggs revealed that the eggs of the outbred herbivores were more likely to be lost by predation, parasitism or plant hypersensitive responses than inbred eggs. This difference did not lead to differences in the realized fecundity as the number of hatched larva did not differ between inbred and outbred herbivores. Thus, the strength of inbreeding depression in herbivores decreases when their natural enemies are involved. Plant inbreeding did not alter the attraction of natural enemies of the eggs. We conclude that inbreeding can significantly alter the interactions of plants and herbivores at different life-history stages, and that some of these alterations are mediated by the natural enemies of the herbivores.

近交可深刻影响植物与植食性昆虫，以及植食性昆虫天敌之间的互作关系。本研究探究了植物近交如何影响专食性植食昆虫（specialist herbivore）的产卵偏好，同时验证了植物与植食性昆虫的近交是否会改变植食性昆虫卵的被捕食、寄生概率。在针对专食性植食蛾类白斑陌夜蛾（Abrostola asclepiadis），以及近交与远交的鹅绒藤（Vincetoxicum hirundinaria）植株的实验室偏好试验中，我们发现植食性昆虫更倾向于在远交植株上产卵。通过设置搭载近交或远交植食性昆虫卵的近交与远交植株的田间试验，结果显示：远交植食性昆虫的卵相比近交卵，更易因被捕食、寄生或植物超敏反应（hypersensitive response）而丢失。由于近交与远交植食性昆虫的孵化幼虫数量并无显著差异，该差异并未导致实际繁殖力（realized fecundity）的不同。因此，当存在天敌时，植食性昆虫的近交衰退（inbreeding depression）强度会降低。植物近交并未改变卵的天敌的趋性。综上，我们认为近交可显著改变植物与植食性昆虫在不同生活史阶段的互作关系，且其中部分改变由植食性昆虫的天敌所介导。