The Immature Stages, Biology, and Phylogenetic Relationships of Rotunda rotundapex (Lepidoptera: Bombycidae)

Phylogenetic relationships and historical biogeography of silkmoths (Lepidoptera: Bombycidae) suggest an origin in Southern Gondwana

Silkmoths (Bombycidae) have a disjunct distribution predominantly in the Southern Hemisphere and Asia. Here we reconstruct the phylogenetic history of the family to test competing hypotheses on their origin and assess how vicariance and long-distance dispersal shaped their current distribution. We sequenced up to 5,074 base pairs from six loci (COI, EF1-α, wgl, CAD, GAPDH, and RpS5) to infer the historical biogeography of Bombycidae. The multilocus dataset covering 20 genera (80 %) of the family, including 17 genera (94 %) of Bombycinae and 3 genera (43 %) of Epiinae, was used to estimate phylogenetic patterns, divergence times and biogeographic reconstruction. Dating estimates extrapolated from secondary calibration sources indicate the Bombycidae stem-group originated approximately 64 Mya. The subfamilies Epiinae (South America) and Bombycinae (Australia, Asia, East Palaearctic, and Africa) were reciprocally monophyletic, diverging at c. 56 Mya (95 % credibility interval: 66-46 Mya). The 'basal' lineage of Bombycinae - Gastridiota + Elachyophtalma - split from the rest of Bombycinae c. 53 Mya (95 % credibility interval: 63-43 Mya). Gastridiota is a monobasic genus with a relictual distribution in subtropical forests of eastern Australia. The Oriental and African genera comprised a monophyletic group: the Oriental region was inferred to have been colonized from a long-distance dispersal event from Australia to South-East Asia c. 53 Mya or possibly later (c. 36-26 Mya); Africa was subsequently colonized by dispersal from Asia c. 16 Mya (95 % credibility interval: 21-12 Mya). Based on the strongly supported phylogenetic relationships and estimates of divergence times, we conclude that Bombycidae had its origin in the fragment of Southern Gondwana consisting of Australia, Antarctica and South America during the Paleocene. The disjunction between South America (Epiinae) and Australia (Bombycinae) is best explained by vicariance in the Eocene, whereas the disjunct distribution in Asia and Africa is best explained by more recent dispersal events.

Phylogenetic relationships among Bombycinae (Lepidoptera, Bombycoidea, and Bombycidae) based on mitochondrial genomes

The subfamily Bombycinae Latreille, [1802] is an important silk-producing group, including well-known economical insects. Although there are many studies on the development of these economic insects, the relationships between genera/species of this subfamily are still unclear. Two data sets of mitochondrial genomes, 13 protein-coding genes (13PCGs) and 13PCGs-AA, were used to estimate phylogenetic relationships based on the maximum likelihood and Bayesian inference methods. The results strongly support the subfamily Bombycinae as a monophyletic group divided into two clades.

Research Progress on Oviposition-Related Genes in Insects

Oviposition-related genes have remained a consistent focus of insect molecular biology. Previous research has gradually clarified our mechanistic understanding of oviposition-related genes, including those related to oviposition-gland-related genes, oogenesis-related genes, oviposition-site-selection-related genes, and genes related to ovulation and hatching. Moreover, some of this research has revealed how the expression of single oviposition-related genes affects the expression of related genes, and more importantly, how individual node genes function to link the expression of upstream and downstream genes. However, the research to date is not sufficient to completely explain the overall interactions among the genes of the insect oviposition system. Through a literature review of a large number of studies, this review provides references for future research on oviposition-related genes in insects and the use of RNAi or CRISPR/Cas9 technology to verify the functions of oviposition-related genes and to prevent and control harmful insects.

The complete mitochondrial genome of Rotunda rotundapex (Miyata & Kishida, 1990) (Lepidoptera: Bombycidae)

Rotunda rotundapex (Miyata & Kishida, 1990) is a silk moth identified in Korea. We completed its mitochondrial genome which is 15,298 bp long and the shortest mitogenome of Bombycidae s.str. It includes 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNAs, and a control region. Comparison with COI sequence of Taiwan isolate suggests the Korean population of this species can be a novel species. Gene order of R. rotundapex mitogenome is conserved as in other Bombycidae species. Phylogenetic trees show that R. rotundapex is closely related to genus Rondotia.