Larval host phylodiversity of Acronicta (Lepidoptera: Noctuidae: Acronictinae)

Moths and caterpillars of the noctuid genus Acronicta Oschenheimer, known as the dagger moths, have captured the imaginations of taxonomists and systematists around the world. Morphologically enigmatic adults and highly variable larvae prompted A.R. Grote (1895) to proclaim "There would seem to be no genus which offers a more interesting field to the biologist for exploration". The larvae sport an assortment of colors, patterns, postures, setal types, behaviors, color changes, and mimicry complexes. This larval diversity presents an evolutionary puzzle: how did such extreme morphology evolve within one genus? There are an estimated 200 species, primarily associated with temperate forests. It is hypothesized that changes in host plant use, i.e. switching hosts, or switching from a more generalized to a more specialized diet, will lead to phenotypic evolution. This study presents a molecular phylogeny (7 nuclear genes and one mitochondrial gene) of most North American Acronicta species with a selection of European and Asian taxa. Lab rearing and a thorough literature search yielded a carefully curated database of host records. Using a recently published Angiosperm phylogeny, these host records were used to calculate host phylodiversity (HPD) for each species in the Acronicta phylogeny. HPD values were mapped onto the Acronicta phylogeny to explore relationships between phylogeny, host plant use, and morphology.