Do Induced Responses Mediate the Ecological Interactions Between the Specialist Herbivores and Phytopathogens of an Alpine Plant?
Gregory Röder, Martine Rahier, Russell E. Naisbit
PLoS ONE 6(5): e19571. doi:10.1371/journal.pone.0019571, 2011
The alpine plant, Adenostyles alliariae, has three specialist natural enemies, the leaf beetles Oreina elongata and Oreina cacaliae, and the phytopathogenic rust Uromyces cacaliae. Only Oreina cacaliae is not a single host specialist and it only infects one other species of plant. These four species must interact as host and associates and all must successfully reproduce during a very short alpine summer. For the beetles to survive and reproduce they must reach a certain size by end of season or they won’t last the winter. In addition, the beetle species avoid rust infected plants. This may be as close to a closed system as one can get in the biological world and acts as a model of host/associate interactions. Plants have two active defensive systems that respond to attacks, the jasmonic acid (JA) pathway and the salicylic acid (SA) pathway, which is sort of analogous to the nervous system and the immune system in animals in respect to combating predators.
Results showed that even specialists with immunity to the plants main chemical defenses are effected by the induced pathways. In addition, the results showed that there is some asymmetric cross-talk between the two induced response pathways. This represents a test of a system under natural conditions and the interactions of a plant in controlling three specialist predators.