Studies On The Systematics Of Bombyx Linnaeus,1758from China(Lepidoptera:Bombycoidea)

The genus Bombyx belongs to Bombycini, Bombycidae, Lepidoptera. The Bombycoidea family contains about40genera and350species. Most of them except for Bombyx mori, an important economic insect, are economically important pests for agriculture, forestry and horticulture industry. Bombycidae is widely distributed in the world, and is one of the important elements of the global zoological fauna and biodiversity., Bombyx names silkworm moths in English, is mainly distributed in Ethiopia and Japan. In general, the final instar larvae of Bombyx cocoon to pupate. Apart from the domesticated species Bombyx mori, other species of Bombyx can cocoon, too, but their cocoon are in low qualities, therefore they not be developed for utilization. Because most of them are feeding on leaves of Morus alba L., they become pests to mulberry sericulture industry, such as Bombyx mandarina, etc.In view of the most species of Bombyx that harm to many species of Morus and thus put an impact on our sericulture industry, still with some objections in some species’ taxonomic status. This study will go through extensive investigations in the field, using external morphological and molecular data to carry out the systematic taxonomy of Bombyx. This is not only ferret out hidden species of the genus, but can also be found in different geographic populations of the species. At the same time, molecular data can provide clear pictures and gene sequences for the rapid identification of pests. The results can provide with the theoretical and practical significances for effective governance of pests and monitoring.This study summarises the taxonomic history of Bombyx and detailed demonstrates the morphological characteristics of the genus. The main results are as follow.1. Morphological taxonomySeven species are studied in the Bombyx from China based on morphological character. Key to species is provided. According to the morphological characteristics, Rotunda gen. nov.was estabilished based on Bombyx rotundapex Miyata&Kishida as the type species, and Rotunda gen. nov.was estabilished.At the same time, Pictures of6species adults, male genitalia of12pieces and female genitalia of2species are given, providing for the most intuitive reference for the identification of agroforestry, horticulture garden industry Saturniidae insects. For the species with the specimens unchecked, the description are cited from the original documents and related literature.2. Molecular phylogenetic studiesSelected the representative types and10individuals of four species from the Bombyx Linnaeus (Because the gene data of Bombyx mori can be directly obtained from the Gene Bank, it is no need to repeat the experiments), and Triuncina brunnea, Rondotia lineata, Carectum huananensis as their representative relatives genera and species to discusse the molecular systems of Bombyx L., based on mitochondrial gene COI, nuclear gene18S and28S sequence fragments, a total of2642bp.Using the neighbor-joining method, maximum parsimony and Bayesian analysis of COI gene and three genes were combined dataset. The results showed that the COI gene is not suitable for the advanced system in phylogenetic analysis, but can be used as species of molecular markers. Using the partition-homogenetiyttest of software PAuP*4.0b1.0(pHT detection) analysis the developmental signal homogeneity test for the gene sequence data sets of COI,18S and28S. The test results showed that the three gene phylogenetic information contained did not conflict. AUP4.0software maximum parsimony heuristic search to analysis for the combined dataset, the result was a length of2041steps of maximum parsimony (consistency index CI:0.517;retention index RI:0.770;consistent scaling index RC:0.398), same to topology NJ tree. Bayesian phylogenetic tree was constructed based jModelTestO.1.1the LhRT test results, selected with the GTR+I model application MrBayes3.1phylogenetic analysis, running1,100,000generations, the standard deviation of split frequency0.003878, all parameters potential standard reduction factor (PSRF) were1.0000, molecular phylogenetic tree topology with the MP tree, each branch of the Bayesian posterior probability was generally equal to or close to1.00(Figure20).