Anthropogenic host plant expansion leads a nettle-feeding butterfly out of the forest: consequences for larval survival and developmental plasticity in adult morphology

Recent anthropogenic eutrophication has meant that hostplants of nettle-feeding insects became quasi-omnipresent in fertile regions of Western Europe. However, hostplant resource quality – in terms of microclimate and nutritional value – may vary considerably between the ‘original’ forest habitat and ‘recent’ agricultural habitat. Here, we compared development in both environmental settings using a split-brood design, so as to explore to what extent larval survival and adult morphology in the nettle-feeding butterfly Aglais urticae are influenced by the anthropogenic environment. Nettles along field margins had higher C/N-ratios and provided warmer microclimates to larvae. Larvae developed 20% faster, and tended to improve their survival rates, on the agricultural land compared to woodland. Our split-brood approach indicated plastic responses within families, but also family effects in the phenotypic responses. Adult males and females had darker wing pigmentation in the drier and warmer...