Should grape moth larval immunity help explaining resistance against natural enemies?

8 pagesInternational audienceIn tritrophic systems (plants, phytophagous insects and natural enemies), host plantvariation often keys the relative performance of both the herbivore and its associated naturalenemies. In bottom-up effects, host plants could affect the fitness of phytophagous insectsincluding growth rate and adult fertility. These effects are indirectly reflected in parasitoidswhose success depends on their host quality. For instance, nutrient deficiency or/and toxicdefensive compounds of the plants could slow-down the development of herbivorous insects,thus extending the window of vulnerability of attacks by natural enemies.The immune system is arguably the most common resistance mechanisms used byphytophagous insects against natural enemies such as parasites and parasitoids. However, only alimited number of studies have really linked tritrophic interactions and immune defenses ofphytophagous insects. Our work considers two grape moths, the European grapevine moth,Lobesia botrana, and the European grapeberry moth Eupoecilia ambiguella.In this study, we have tested the influence of different grapevine varieties on the baselinelevel of three immune parameters (concentration of haemocytes, activity of the prophenoloxidasesystem and antimicrobial activity) of larvae of the European grapevine moth. In this presentationwe discuss the results obtained in this experiment and their effects and importance in tritrophic