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Abstract

Specialist herbivores have often evolved highly sophisticated mechanisms to counteract defenses
mediated by major plant secondary-metabolites. Plant species of the herbivore host range often
display high chemical diversity and it is not well understood how specialist herbivores respond to this
chemical diversity. Pieris larvae overcome toxic products from glucosinolate hydrolysis, the major
chemical defense of their Brassicaceae hosts, by expressing nitrile-specifier proteins (NSP) in their gut.
Furthermore, Pieris butterflies possess so-called major allergen (MA) proteins, which are multi-domain
variants of a single domain major allergen (SDMA) protein expressed in the guts of Lepidopteran larvae.
Here we show that Pieris larvae fine-tune NSP and MA gene expression depending on the glucosinolate
profiles of their Brassicaceae hosts. Although the role of MA is not yet fully understood, the expression
levels of NSP and MA in larvae that fed on plants whose glucosinolate composition varied was
dramatically changed, whereas levels of SDMA expression remained unchanged. In addition, we found
a similar regulation pattern among these genes in larvae feeding on Arabidopsis mutants with different
glucosinolate profiles. Our results demonstrate that Pieris larvae appear to use different host plant adaptive genes to overcome a wide range of glucosinolate profiles in their host plants.