Are Sequestered Allelochemicals Detriments or Benefits to Wasp and Fly Parasitoids?

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Host plant chemistry as a mediator of the interactions between plants, herbivores and the natural enemies of those herbivores is a key concept in evolutionary ecology. Recently, higher trophic levels (and therefore predation) have assumed importance in accounting for population dynamics and evolutionary relationships between plants and insects. Rigorous tests in model systems are still needed to understand the intricacies of tritrophic interactions and, in particular, to clarify the role of chemistry as a mediator of direct and indirect interactions between different trophic levels. This collaborative project will examine how the sequestration of plant chemicals mediates multi-trophic interactions with special reference to an understudied group of natural enemies, wasp and fly parasitoids. A model system of plants containing iridoid glycosides, three pairs of closely related caterpillar species - one species in each pair that does and one that does not sequester iridoid glycosides - and their wasp and fly parasitoids will be used to investigate the role of sequestered plant chemicals in herbivore-parasitoid interactions. Two sets of laboratory experiments will be initiated to examine the effects of chemical sequestration on parasitoid success. Chemical content of caterpillar diets will be manipulated by painting plant extracts onto leaves of caterpillar host plants.Broader impacts: This will be one of only a few studies to examine the role of sequestered chemicals on parasitoid success. The investigators have extensive experience training undergraduate and graduate students in all the techniques and experimental methods described in the proposal and will continue their active involvement with important training programs such as Research Experience for Undergraduates (REU), the Ecological Society of America's SEEDS program for minorities, the Louisiana Alliance for Minority Participation, the University of Colorado's Undergraduate Research Opportunities program and Summer Minority Access to Science and Technology program, and Fulbright's LASPAU program for training faculty from other countries.