Differential gene expression, depending on host plant diet, has been found in the larval mid-gut of the polyphagous butterfly Polygonia c-album. Expression similarities between the hosts elm/sallow and between elm/stinging nettle suggest that there are special patterns of genes for utilizing trees and others for urticalean rosids.
In order to assess the importance of different genes tailored to host use, we investigated the costs of switching larval diet. Negative effects were expected to be more pronounced when switching between nettle/sallow than between elm/nettle (urticalean rosids) or elm/sallow (trees) since similarities in mid-gut gene expression are fewer.
However, larvae seemed surprisingly good at adjusting to new environments. Although costs were found after a single switch from sallow to nettle in the 3rd instar as well as on a daily basis the results were not consistent. More surprisingly, we found evidence that costs are involved with a single diet switch to elm. Results suggest rapid physiological adjustment to the new environment, signifying that the induced gene expression is reversible or at least does not seem to inhibit the induction of another gene complex.