Host Plants as Mediators of Caterpillar-Natural Enemy Interactions

Abstract

Over the past several decades, it has become increasingly clear that host plant identity plays an important role in mediating interactions between caterpillars and their natural enemies. Interspecific variation in plant traits, including both chemical and physical features, can influence natural enemies directly or can function indirectly, via effects on caterpillar behavioral and/or physiological responses to their host plants. In this chapter, we review the considerable literature on how species-specific differences in host plant chemistry, information resources, morphology, provisioning, and architecture influence caterpillar-natural enemy interactions. We highlight some of our relevant work on multitrophic interactions involving caterpillars of the silver-spotted skipper (Epargyreus clarus) and their various leguminous host plants and natural enemies. We also describe less well-studied indirect interactions we think may provide fruitful areas of exploration, including the potential role of plant traits in influencing the expression or effectiveness of caterpillar antipredator defensive behaviors or that restrict plants to particular microhabitats that differentially expose their associated caterpillars to natural enemies.KeywordsDefenseEncapsulationExtrafloral nectarHerbivore-induced plant volatilesHost plantIndirect interactionsInsect herbivoreMyrmecophyteOntogenyParasitoidPlant architecturePredatorRegurgitationSecondary chemistrySequestrationShelterSlow-growth-high-mortality hypothesisTrichomesTrophic cascade