Revisiting the evolution of Ostrinia moths with phylogenomics (Pyraloidea: Crambidae: Pyraustinae)

Reconstructing a robust phylogenetic framework is key to understanding the
ecology and evolution of many economically important taxa. The crambid
moth genus Ostrinia contains multiple agricultural
pests, and its classification and phylogeny has remained controversial due
to the paucity of characters and the lack of clear morphological
boundaries for its species. To address these issues, we inferred a
molecular phylogeny of Ostrinia using a phylogenomic
dataset containing 498 loci and 115,197 nucleotide sites and examined
whether traditional morphological characters corroborate our molecular
results. Our results strongly support the monophyly of one of
the Ostrinia species groups but surprisingly do not
support the monophyly of the other two. Based on the extensive
morphological examination and broadly representative taxon sampling of the
phylogenomic analyses, we propose a revised classification of the
genus, defined by three species groups (Ostrinia
nubilalis species group, Ostrinia
obumbratalis species group, and Ostrinia
penitalis species group), which differs from the traditional
classification of Mutuura & Munroe (1970). Morphological
and molecular evidence reveal the presence of a new North American
species, O. multispinosa Yang, sp.n., closely
related to O. obumbratalis. Our analyses indicate that
the Ostrinia ancestral larval host preference was for
dicots, and that O. nubilalis (European corn borer)
and O. furnacalis (Asian corn borer) independently
evolved a preference for feeding on monocots (i.e., maize). Males of a
few Ostrinia species have enlarged, grooved midtibiae
with brush organs that are known to attract females during courtship.
Males of the ancestral Ostrinia had relatively small
midtibiae without brush organs, suggesting that the
ancestral mate-finding behavior instead involved
pheromones emitted by females. Our study provides a
strong evolutionary framework for this agriculturally important insect
lineage.