Data from: Transcriptional profile and differential fitness in a specialist milkweed insect across host plants varying in toxicity

Interactions between plants and herbivorous insects have been models for
theories of specialization and coevolution for over a century.
Phytochemicals govern many aspects of these interactions and have fostered
the evolution of adaptations by insects to tolerate or even specialize on
plant defensive chemistry. While genomic approaches are providing new
insights into the genes and mechanisms insect specialists employ to
tolerate plant secondary metabolites, open questions remain about the
evolution and conservation of insect counter-defenses, how insects respond
to the diversity defenses mounted by their host plants, and the costs and
benefits of resistance and tolerance to plant defenses in natural
ecological communities. Using a milkweed-specialist aphid (Aphis nerii)
model, we test the effects of host plant species with increased toxicity,
likely driven primarily by increased secondary metabolites, on aphid life
history traits and whole body gene expression. We show that more toxic
plant species have a negative effect on aphid development and lifetime
fecundity. When feeding on more toxic host plants with higher levels of
secondary metabolites, aphids regulate a narrow, targeted set of genes,
including those involved in canonical detoxification processes (e.g.,
cytochrome P450s, hydrolases, UDP-glucuronosyltransferases, and ABC
transporters). These results indicate that A. nerii marshal a variety of
metabolic detoxification mechanisms to circumvent milkweed toxicity and
facilitate host plant specialization, yet, despite these detoxification
mechanisms, aphids experience reduced fitness when feeding on more toxic
host plants. Disentangling how specialist insects respond to challenging
host plants is a pivotal step in understanding the evolution of
specialized diet breadths.