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Abstract

The tremendous diversity of plants and herbivores has arisen from a coevolutionary relationship characterized by
plant defense and herbivore counter adaptation. Pierid butterfly species feed on Brassicales plants that produce
glucosinolates as a chemical deterrent against herbivory. In turn, the larvae of pierids have nitrile specifier proteins
(NSPs) that are expressed in their gut and disarm glucosinolates. Pierid butterflies are known to have diversified
in response to glucosinolate diversification in Brassicales. Therefore, each pierid species is expected to have a
spectrum of host plants characterized by specific glucosinolate profiles. In this study, we tested whether the larval
performance of different Pieris species, a genus in Pieridae (Lepidoptera: Pieridae), was associated with plant
defense traits of putative host plants. We conducted feeding assays using larvae of three Pieris species and 10
species of the Brassicaceae family possessing different leaf physical traits and glucosinolate profile measurements.
The larvae of Pieris rapae responded differently in the feeding assays compared with the other two Pieris species.
This difference was associated with differences in glucosinolate profiles but not with variations in physical traits
of the host plants. This result suggests that individual Pieris species are adapted to a subset of glucosinolate
profiles within the Brassicaceae. Our results support the idea that the host ranges of Pieris species depend on larval
responses to glucosinolate diversification in the host species, supporting the hypothesis of coevolution between butterflies and host plants mediated by the chemical arms race.