DNA barcoding evaluation and implications for phylogenetic relationships in ladybird beetles (Coleoptera: Coccinellidae)

Ladybird beetles (Coleoptera: Coccinellidae), with broad morphological diversity, wide geographic distribution and substantial agricultural significance, are a challenging group for taxonomists and phylogenetics. As a promising tool to identify and discover new species, DNA barcoding might offer significant potential for identification, taxonomy and phylogeny of ladybird beetles. In the present study, a total of 1364 COI (cytochrome C oxidase subunit I) sequences representing 128 species from 52 genera of ladybird beetles were screened for barcoding evaluation and phylogenetic analysis. Our results from the barcoding analysis revealed that COI displays a similar level of species identification efficiency (nearly 90%) either based on Kimura two-parameter (K2P) distances calculation or on simplified neighbour-joining (NJ) tree construction. The phylogenetic relationships within the family Coccinellidae was analyzed by Bayesian-inference (BI) method. The phylogenetic results confirmed the monophyly of the subfamilies Microweisinae and Coccinellinae sensu Ślipiński (2007), and suggested that the subfamilies Coccidulinae, Chilocorinae and Scymninae are paraphyletic. However, the phylogenetic relationships among different subfamilies are not clearly defined and thus remain to be thoroughly studied. Overall, our study confirmed the usefulness of DNA barcoding for coccinellid species identification and phylogenetic inference.