AbstractThe diversity of phytophagous insects is often attributed to the success of land plants in the framework of ecological speciation. Several hypotheses have been proposed to explain host plant driven insect diversification in a phylogenetic context and have mostly been explored using Lepidoptera. We posit that Miridae are a great system to examine these hypotheses because they are one of the largest primarily phytophagous insect families and include many species with narrow host repertoire. Focusing on the species‐rich Phylinae (>2700 spp.), we generate the most taxon‐rich phylogeny published to date and for the first time estimate divergence times and trace the evolution of host plant associations across the group. Focusing on two clades of oak‐associated phylines, we further examine if diversification in these insects and their hosts coincided or if the insects tracked their hosts. We find that Phylinae diverged from their orthotyline sister group before the end of the Cretaceous, tribal‐level taxa diversified throughout the Paleogene, and diversification within genera mostly occurred in the Neogene. Host plant repertoire reconstructions at the family level show transitions from stenophagy to polyphagy are more common than the reverse. We reconstructed the ancestral phyline host as ambiguous, followed by Asterales throughout most of the deep splits. Species‐level divergences in the two oak‐associated clades coincide with those in oaks, a pattern is that is consistent with the hypothesis that these plant bugs may have cospeciated with their hosts. Our study shows that Phylinae are a suitable system to further test hypotheses on ecological speciation of plants and insects but will require more robust phylogenetic hypotheses of the group.
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