title: Costs and benefits of plant allelochemicals in herbivore diet in a multi enemy world.
abstract: Sequestration of plant defensive chemicals by herbivorous insects is a way of defending themselves against their natural enemies. Such herbivores have repeatedly evolved bright colours to advertise their unpalatability to predators, i.e. they are aposematic. This often comes with a cost. In this study, we examined the costs and benefits of sequestration of iridoid glycosides (IGs) by the generalist aposematic herbivore, the wood tiger moth, Parasemia plantaginis. We also asked whether the defence against one enemy (a predator) is also effective against another (a parasitoid). We found that the larvae excrete most of the IGs and only small amounts are found in the larvae. Nevertheless, the amounts present in the larvae are sufficient to deter ant predators and also play a role in defence against parasitoids. However, excreting and handling these defensive plant compounds is costly, leading to longer development time and lower pupal mass. Interestingly, the warning signal efficiency and the amount of IGs in the larvae of P. plantaginis are negatively correlated; larvae with less efficient warning signals contain higher levels of chemical defence compounds. Our results may imply that there is a trade-off between production and maintenance of coloration and chemical defence. Although feeding on a diet containing IGs can have life-history costs, it offers multiple benefits in the defence against predators and parasitoids.
authors: Department of Biology and Environmental Science, Centre of Excellence in Biological Interactions, University of Jyvaskyla, P.O. Box 35, 40014, Jyväskylä, Finland. jhtalsma@hotmail.com.
authors: J H
authors: JH
authors: Reudler
authors: Department of Biology and Environmental Science, Centre of Excellence in Biological Interactions, University of Jyvaskyla, P.O. Box 35, 40014, Jyväskylä, Finland.
authors: C
authors: C
authors: Lindstedt
authors: Department of Chemistry, Laboratory of Applied Chemistry, University of Jyvaskyla, P.O. Box 35, 40014, Jyväskylä, Finland.
authors: H
authors: H
authors: Pakkanen
authors: Department of Biology and Environmental Science, Centre of Excellence in Biological Interactions, University of Jyvaskyla, P.O. Box 35, 40014, Jyväskylä, Finland.|Department of Environmental Sciences, University of Helsinki, P.O. Box 65, 00014, Helsinki, Finland.
authors: I
authors: I
authors: Lehtinen
authors: Department of Biology and Environmental Science, Centre of Excellence in Biological Interactions, University of Jyvaskyla, P.O. Box 35, 40014, Jyväskylä, Finland.
authors: J
authors: J
authors: Mappes
mesh_terms: D000818:Animals; D001000:Ants; D003116:Color; D003362:Cost-Benefit Analysis; D004032:Diet; D060467:Disease Resistance; D060434:Herbivory; D057889:Iridoid Glycosides / Q000378:metabolism*; D007814:Larva / Q000254:growth & development; D009036:Moths / Q000254:growth & development / Q000378:metabolism / Q000469:parasitology / Q000502:physiology*; D010675:Pheromones / Q000378:metabolism*; D010858:Pigmentation; D010944:Plants / Q000737:chemistry*; D011235:Predatory Behavior
chemical_list: D057889:Iridoid Glycosides; D010675:Pheromones
keywords: Bio assay; Cotesia villana; Iridoid glycosides; Plantago lanceolata; Warning signal