The family Bombycidae (sensu Minet, 1994) is a diverse group of species belonging to the superfamily Bombycoidea. It is an economically important group of moth species, containing well-known silk-producing insects, as well as many pests of agriculture and forestry. The morphology-based hypothesis of Minet (1994) on the composition of Bombycidae is in conflict with subsequent phylogenetic hypotheses for the superfamily based on nuclear genes. In this paper, the complete mitochondrial genomes of nine species of Bombycidae are presented for the first time. Based on these genomes, four dataset partitions and three gblocks parameter settings, phylogenetic relationships among Bombycidae were reconstructed using maximum likelihood and Bayesian inference methods. Bombycidae was confirmed as a polyphyletic group, with the traditional subfamilies Prismostictinae and Oberthueriinae forming a single well-supported clade that is distant to Bombycinae. The phylogenetic relationships within Bombycoidea were supported as ((((Bombycinae, Sphingidae), Saturniidae), (Prismostictinae, Oberthueriinae)), Eupterotidae).

The bombycid moth, Andraca theae (Matsumura) (Lepidoptera: Bombycoidea) is an important pest of tea in southeastern China. In the present study, the mitochondrial genome (mitogenome) of A. theae was amplified by polymerase chain reaction and sequenced. The complete mitogenome of A. theae, encoding 37 genes, was 15,737 bp in length (Genbank no. KX365419), and consisted of 13 protein-coding genes (PCGs), 22 tRNA genes, 2 ribosomal RNA genes and an adenine (A) + thymine (T)-rich region (AT-rich region). The gene order of A. theae mitogenome was typical for Lepidoptera mitogenomes. Except for cox1, which started with CGA, all other 12 PCGs started with ATN. Eleven of the 13 PCGs ended with TAA, expect for cox1 and cox2, which ended with a single T. The maximum likelihood method and the Bayesian method were used to analyze the phylogenetic relationship among 22 representative bombycoid species with a matrix consisting of the 13 PCGs of the mitogenomes of the 22 species. The topological structures of the two phylogenetic trees we constructed were almost identical, with the results indicating that the bombycid species, including A. theae, clustered into a single clade with a bootstrap value of 58% and a posterior probability of 0.98. The phylogenetic relationship among the Bombycoidea species analyzed was Lasiocampidae + (Bombycidae + (Saturniidae + Sphingidae)) which was supported by a high bootstrap value of 100% and a posterior probability of 1.00.

As a serious forest pest on coniferous trees, Dendrolimus kikuchii has caused widespread concern in China. Here, its complete mitochondrial genome (mitogenome) has been sequenced with 15,382 bp in length. The mitogenome has a base composition of A (40.87%), T (37.83%), C (13.43%), and G (7.87%), and consists of 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and an A þ T-rich region. The phylogenetic relationships among the lasiocampid species were (Trabala vishnouþ ((Apatelopteryx phenaxþ Euthrix laeta) þ (Dendrolimus kikuchiiþ (D. spectabilisþ (D. tabulaeformis þ D. punctatus))))), which were supported by a posterior probability of 1.00 and a high bootstrap value of 100%.

The complete mitochondrial genome (mitogenome) of Bombyx lemmepauli Lemée has been sequenced with 15,801 bp in length (Genbank no. KY620270), and has a base composition of A (43.17%), G (7.40%), C (11.90%), and T (37.86%). Similar to other bombyciod species, it contains a typically conserved structure including 13 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes, and an A + T-rich region. Excepting cox1 started with CGA, the start codons of the other 12 PCGs were ATN. Eleven of the 13 PCGs ended with TAA, expect for cox1 and cox2 , which ended with a single T. The complete mitogenome sequence provided here would be useful for further understanding the evolutional position of B. lemeepauli , which is a key species to relate the famous resource insect B. mori and the important insect pest Rondotia menciana (Lepidoptera: Bombycidae).

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