UC Berkeley

This dissertation considers insect ecology from two perspectives, at two scales of space and time, using two different methodologies. In the first chapter, I investigate the direct interactions between plants and insects through plant defenses against herbivory. I explore the effect of plant exposure to natural smoke on herbivore growth, using the model system Nicotiana attenuata and Manduca sexta. Despite finding no effect in these tests, I believe that the mechanisms for potential impacts of smoke exposure on plant defenses are convincing enough to warrant further study.

In the second and third chapters, I investigate the geographic patterns of genomic diversity in an herbivorous insect that underwent a dramatic host switch to become an important invasive agricultural pest. The Colorado potato beetle, Leptinotarsa decemlineata, is one of the most successful insect pests of agriculture. However, its evolutionary origins as an insect pest of potato remain unclear. I conducted reduced genome sequencing using RADseq on samples collected from across the proposed native range of Mexico and from the East Coast of the USA in the introduced range. I describe the geographic population structure of the beetle, examine the genomic diversity across the samples, and conduct a phylogenomic analysis.