Plasticity for the win: Flexible transcriptional response to host plant switches in the comma butterfly (Polygonia c‐album)

Abstract

AbstractGeneralist plant‐feeding insects are characterised by a broad host repertoire that can comprise several families or even different orders of plants. The genetic and physiological mechanisms underlying the use of such a wide host range are still not fully understood. Earlier studies indicate that the consumption of different host plants is associated with host‐specific gene expression profiles. It remained, however, unclear if and how larvae can alter these profiles in the case of a changing host environment. Using the polyphagous comma butterfly (Polygonia c‐album) we show that larvae can adjust their transcriptional profiles in response to a new host plant. The switch to some of the host plants, however, resulted in a larger transcriptional response and, thus, seems to be more challenging. At a physiological level, no correspondence for these patterns could be found in larval performance. This suggests that a high transcriptional but also phenotypic flexibility are essential for the use of a broad and diverse host range. We furthermore propose that host switch tests in the laboratory followed by transcriptomic investigations can be a valuable tool to examine not only plasticity in host use but also subtle and/or transient trade‐offs in the evolution of host plant repertoires.