PARENT SESSION
Poster Session #32: Plant-Animal Interactions I.
Wednesday, August 7. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Causes and consequences of variation in Piper chemistry.

BRAUNER, R.^*,1, TOBLER, M.¹, STIREMAN, J.¹, LETOURNEAU, D.², DODSON, C.³, DYER, L.¹, ¹ Tulane University, New Orleans, LA² University of California, Santa Cruz, CA³ Mesa State College, Grand Junction, CO

ABSTRACT- The allocation of resources to different defenses is limited by resources but also may be constrained by higher trophic levels. Piper cenocladum plants provide shelter and food rewards for ant mutualists, which provide defense against specialist herbivores. The plants may also be defended against generalist herbivores by three amides. The larvae of a predatory beetle displace these ant mutualists and continue to stimulate production of food bodies. To test for multi-trophic level interactions between ants, beetles and plant chemistry, we examined the causes and consequences of variation in secondary compounds in P. cenocladum plants occupied by ants, plants occupied by beetles, and plants from which ants had been excluded. Amide concentration was highest in plants from which ants had been excluded and lowest in plants occupied by beetles. In addition to removing biotic defenses of P. cenocladum plants, beetles deplete plant resources and decrease the concentration of chemical defenses in plant materials. In order to test the effectiveness of P. cenocladum amides against naive generalists, we added combinations of one, two, or all three amides to the diets of Spodoptera frugiperda larvae. Piper cenocladum amides act synergistically to increase herbivore development times and lower growth rates and pupal mass. We plan to compare results from this study to an identical study on the causes and consequences of amide variation in the closely related non-ant plant, Piper imperiale.

KEY WORDS: plant-insect interactions, piper cenocladum, secondary metabolite, amide