Studies On Artificial Diet Eating Habit Of Silkworm And Construction Of The Silkworm Fingerprints

The purpose of the study on the heredity about silkworm feeding habit on artificial diet is to find out the differences of the feeding habits among silkworm varieties or individuals, and the physiological causes, and then, analyze the factors influence the feeding habits and the genetic mode. This will pave the path for the breeding of silkworm varieties that suitable for artificial diet. The study will also provide the theory for improving artificial diet, breeding technology, and the uniform of silkworm development and especially for the breeding of omnivorous silkworm varieties that adapt to artificial diet.The silkworm (Bombyx mor L.), which gradually formed differently in long term ecological conditions, is one of the most important economic insects. The classic categorization relies mainly on economic and morphological treats. However, economic treats fluctuates due to environmental change and morphological treats have little difference among silkworm varieties. The construction of the silkworm DNA fingerprints applying SSR(Simple Sequence Repeats) will provide us with scientific bases for silkworm identification, heredity appraisal and exploitation.1. Studies of silkworm(Bombyx ntori L) feeding habits on mulberry free artificial diet386 silkworm varieties were fed with mullberry free artificail diet to breed the omnivorous races and invest the ingestion. The ingestion differences are clear-cut among different varieties. The monovolting varieties of Chinese system have the highest ingestion rate whlie the multivolting have the lowest. It is found that there are many euryphagy varieties preserved in China, especially Chinese system. They have great value in research.2. Selection of the silkworm varieties that ingest artificial diets and analysis of feeding habit heredityIn order to obtain a pure line omnivorous system of silkworm variety which is suitable for artificial diet, two varieties, Selected 01 and Selected 02, were chosen for further selection in continuous generations. The average feeding ratio on mulberry free artificial diet of newly hatched larve reached 99.0% after the selection. Chinese 10, which has high ingestion ratio, is intercrossed with 1015 that has low ingestion ratio. The F1, F2 and BC1 generations are fed with mulberry free artificial diets and the ingestion are examined. The result shows that the ingestion of the diet is recessive inheritance and controlled by a major gene locates at autosome. And modificators genes also contribute to this.3. The construction of silkworm fingerprints applying SSR molecular markersThe fingerprints of 96 Chinese bivoltinism silkworm varieties were constructed applyingmicrosatellite markers (Simple Sequence Repeat, SSR). The results of PCR products showed perfect polymorphism and fingerprint characteristic except two pairs of the markers. The 96 silkworm varieties could be distinguished by several groups of markers and the bands were clear and stable. The plentifulness of SSR polymorphism in silkworm genome and the differences of the polymorphism among different silkworm races indicate the advantage of SSR in the construction of silkworm DNA fingerprints and analysis of inheritance diversity, and show the foreground of application of SSR in silkworm molecular marker technology.4. Analysis of SSR phylogeneticThe genome of 96 Chinese bivoltinism silkworm varieties were amplified applying 57 pairs microsatellite (SSR) markers. There are 507 valid bands amplified altogether. The number of the bands amplified by single pair of markers varies from 1 to 24, and the average is 8.9/primers. The length of the bands varies from 90bp to 370bp and shows microsatellite (SSR) markers can reflect the polymorphism among silkworm races. A phylogenetic tree was constructed applying UPGMA clustering method.