Mutualism has its limits: consequences of asymmetric interactions between a well-defended plant and its herbivorous pollinator

Concern for pollinator health has focused on social bees and their agricultural services, but not all pollinators are bees, and their ecosystem services also promote biodiversity and conservation. Pollinating herbivores generate ecological conflicts when they utilize the same plant as a nectar source and larval host. We tracked individual-level metrics of pollinator health – growth, survivorship, fecundity – across the life cycle of a pollinating herbivore, the hawkmoth Hyles lineata, through its interactions with Oenothera harringtonii, a rare plant polymorphic for the floral volatile (R)-(-)-linalool. Linalool had no impact on moth attraction to O. harringtonii flowers but suppressed oviposition on experimentally supplemented plants. Leaves of O. harringtonii showed robust resistance against herbivory by H. lineata from leaf-disc to wholeplant scales, through poor larval growth and survivorship. Higher larval performance on other Oenothera species indicates that constitutive herbivore...