Abstracts (first author)
Interactive effects of inbreeding in a specialized plant-herbivore interaction
Inbreeding causes inbreeding depression in plant resistance against herbivores, as well as in several fitness-related traits in the herbivores. Furthermore, plant inbreeding may affect herbivore performance due to reduced herbivore resistance or plant nutritional quality. In many natural plant-herbivore systems, both of the interacting species are likely to experience inbreeding and yet, interactive effects of inbreeding of both a host plant and its herbivore have not been extensively studied. We studied the effects of experimental inbreeding of a perennial host plant, Vincetoxicum hirundinaria, and its specialist herbivore, the moth Abrostola asclepiadis, on plant resistance and herbivore performance in four populations. We were particularly interested in how inbreeding of both the host plant and the herbivore affect host and herbivore inbreeding depression in resistance and performance. Our results demonstrate that the expression of inbreeding depression in herbivore performance depends on whether the herbivore was grown on an inbred or on an outbred host plant and this effect varied among herbivore populations. Inbreeding depression in plants was significantly higher when they were consumed by outbred compared to inbred herbivores. Finally, the expression of inbreeding depression in the host plant in terms of resistance varied among plant and herbivore populations. These findings demonstrate that in plant-herbivore interactions inbreeding depression of one species can be altered depending on the inbreeding of the interacting species. Furthermore, our results suggest that when herbivores are inbred, herbivore-induced selection against self-fertilization in plants may diminish.