Interactions between herbivorous insects and their host plants are a central component of terrestrial food webs and a critical topic in agriculture, where a substantial fraction of potential crop yield is lost annually to pests. Important insights into plant–insect interactions have come from research on specific plant defences and insect detoxification mechanisms. Yet, much remains unknown about the molecular mechanisms that mediate plant–insect interactions. Here we use multiple genome-wide approaches to map the molecular basis of herbivory from both plant and insect perspectives, focusing on butterflies and their larval host plants. Parallel genome-wide association studies in the cabbage white butterfly, Pieris rapae, and its host plant, Arabidopsis thaliana, pinpointed a small number of butterfly and plant genes that influenced herbivory. These genes, along with much of the genome, were regulated in a dynamic way over the time course of the feeding interaction. Comparative analyses, including diverse butterfly/plant systems, showed a variety of genome-wide responses to herbivory, as well as a core set of highly conserved genes in butterflies as well as their host plants. These results greatly expand our understanding of the genomic causes and evolutionary consequences of ecological interactions across two of nature’s most diverse taxa, butterflies and flowering plants.
Bibliographical noteFunding Information:
We thank E. Westerman, R. Marquez, L. Southcott, A. Russell and G. Garcia for assistance with experiments and D. Samac for generously providing Medicago sativa seeds. N. Saleh helped with generating the inbred P. rapae material for the sequencing the initial genome assembly. We also thank C. Sahagun for assisting with the butterfly photography. This project was funded by NIH grant GM108626 and NSF grant IOS-1452648 to M.R.K., funds from and University of Pittsburgh, the Pew Charitable Trust and Neubauer funds from the University of Chicago.