DNA sequence variation at the mitochondrial cytochrome oxidase I subunit among pheromotypes of the sibling taxa Diachrysia chrysitis and D. tutti (Lepidoptera: Noctuidae)

We surveyed variation in the mtDNA cytochrome oxidase subunit I (COI) gene in the noctuid sibling species Diachrysia chrysitis and D. tutti, whose taxonomic status has been queried. Taxonomically, these taxa are separated on the basis of wing pattern and time of flight period. Samples were field-collected from different geographical sites where pheromone traps were baited to attract males containing different mixtures of two blends of pheromone components: (Z)-5-decenyl acetate and (Z)-7-decenyl acetate. Most specimens were sequenced over a 709 bp segment of the COI gene. Single specimens each of D. chrysitis and D. tutti were sequenced over a region of 1.5 kilobases. mtDNA variation within and among D. chrysitis and D. tutti is most simply interpreted as DNA polymorphism within a complex of closely related, but well-differentiated pheromotypes. Maximal nucleotide difference per site among haplotypes was 0.28%, which is at the lower end of the range for interspecific MtDNA nucleotide diversity in Lepidoptera. Coefficient of differentiation G(ST) was c. 76.3% +/- 11.7%, a typical value at the intraspecific level. Sequences revealed stable diagnostic differences between pheromotypes irrespective of geographical origin. Identification of pheromone-trapped males based on morphology remained vague and uncorrelated to mtDNA haplotypes. The survey illustrated the potential utility of direct DNA sequencing in assessing lineage structures or taxon limits among moths that have been previously found to be different using the pheromone mate recognition system, but which have not been subjected to DNA analysis. The results of mtDNA analyses presented here support recognition of chrysitis and tutti lineages as presented in previous allozyme studies.