Welcome to Angela Smilanich’s Web Page

Department of Ecology and Evolutionary Biology

Tulane University, New Orleans, LA

Research Interests

Iridoid glycosides

Amides

Research Interests

My research interests include topics in tri-trophic interactions, plant defense theory and the evolution of diet breadth. Specifically, I am interested in the direct and indirect effects of plant secondary metabolites on herbivores and their natural enemies. My current research focuses on the negative effects of plant secondary metabolites on the immune functions of caterpillars. My research takes place in a Costa Rican lowland rainforest and in nearby banana plantations. The banana plantations provide an applied aspect to my research by offering a community in which to study the effects of pesticides and herbicides on non-target organisms. I am also conducting experiments in our lab at Tulane University, investigating the immune response of sequestering and non-sequestering caterpillars. The immune function that I am focusing on is the encapsulation response, which is a cytological and humoral response to any foreign object inside an insect (i.e. parasitoid egg). I hypothesize that secondary metabolites and pesticides are interfering with the encapsulation response in caterpillars, making them vulnerable to parasitoids. The goals of my study are:

(1) Examine the effects of plant toxins on both herbivores and their natural enemies.

(2) Investigate one possible mechanism by which maintenance of herbivore populations

by natural enemies is indirectly enhanced by plant toxins.

Path Diagram of Hypothesis

Silica beads (approximately 80µm in size) that

are injected into caterpillars as a proxy for a

parasitoid egg. The bead on the left shows encapsulation and melanization forming. The bead on the right shows no encapsulation or melanization.

Respiration rates of caterpillars feeding on high toxic diets are significantly higher than caterpillars feeding on low toxic diets.

Junonia coenia (Buckeyes) sequester iridoid glycosides and specialize on plants containing this secondary metabolite.