Study On Isolation,Identification And Prevention Methods Of Two Strains Of Silkworm Pathogenic Bacteria In Yizhouabstract

With the development of west China and the moving sericulture production from east to west,the silkworm industry achieved rapid development in Guangxi.However,because of silkworm disease,this industry was large only in the output and not in the quality.Guangxi is located in the subtropical area,hot humid climate,which is conducive to the breeding and reproduction of pathogenic bacteria,causing more diseases in silkworm.Furthermore,the influenza season is longer,more easily spreading in a lager range.At present,viral and bacterial diseases were common infectious disease mainly occurring in sericulture production.For a long time,viral diseases were thought to be harmer than bacterial diseases which were lack of attention.However,according to the survey,the loss caused by the bacterial disease was larger than by the virus disease in some months(5-9 months).In this paper,two local diseases,bacterial poisoning disease and prodigiosus septicemia,were studied and the results were as following:1 The identification and prevention of the pathogen of silkworm prodigiosus septicemia.The pathogenic bacteria was separated from the silkworm suffering from prodigiosus septicemia in Yizhou.A series of experiments were conducted,including re-inoculation,morphological,physiological and biochemical character,and 16S rRNA sequence analysis.Finally,the bacteria was identified as Serratia marcescens,also known as Bacillus prodigiosus.The drug sensitivity test was conducted,using five antibiotics and three kinds of disinfectants.Results showed that norfloxacin and ciprofloxacin antibiotics inhibited the growth of Serratia marcescens obviously,and bleaching powder,chlorine dioxide and formaldehyde of Serratia marcescens were effective in disinfection.In the drug screening of silkworm Bombyx mori,the effects of ciprofloxacin,norfloxacin and chloramphenicol were consistent with the results of drug sensitivity test,and the best prevention effect came in the 1000mg/L control,with a cure rate of 100%.2 The identification and prevention of the pathogen of silkworm bacterial poisoning diseaseThe pathogenic bacteria was separated from the silkworm suffering from bacterial poisoning disease in Yizhou.A series of experiments were conducted,including re-inoculation,morphological,physiological and biochemical character,and 16S rRNA sequence analysis.Finally,the bacteria was identified as Bacillus thuringiensis.The drug sensitivity test was conducted,using several common antibiotics and disinfectants.Results showed that antibiotics,such as erythromycin,enrofloxacin and ciprofloxacin were effective in treating bacterial poisoning disease.and the effective disinfection time of bleaching powder was short.The analysis of infected law showed that the disease mainly caused by feeding and trauma.After onset,the catalase activity in serum kept increasing in dying,then decreased gradually.