Rapid Detection Of Main Pathogens In Larimichthys Polyactis By Fluorescence Quantitative PCR And The Establishment Of A Disease Warning Model

Since the whole artificial breeding of little yellow croaker(Larimichthys polyactis)was realized for the first time in 2016,various breeding technologies of Larimichthys polyactis have made great progresses,but the situation of disease limits the further improvement of breeding survival rate severely.Among them,Vibrio harveyi,Pseudomonas plecoglossicida,Iridovirus,and Cryptocaryon irritans were the major diseases in larimichthys polyactis.To effectively predict the outbreak time of the above diseases and take preventive and control measures,this study mainly performed the following work:(1)Developed the SYBR Green I fluorescence quantitative PCR detection methods for the above 4 kinds of diseases;(2)Monitored the water quality parameter(temperature,salinity,dissolved oxygen and pH)and quantity of the above pathogens for twenty months;(3)Determined the range of threshold of the pathogens in waters through challenge experiment and quantitative analysis for the effective diseases warning of little yellow croaker;(4)Established the early warning model of Larimichthys polyactis diseases using the wavelet denoising and BP neural network analysis technology.Through testing,we found the minimum detectable concentrations of Vibrio Harvieri,Pseudomonas plecoglossicida,iridovirus and,Cryptocaryon irritans were respectively 1,10,10 and 10 copies/μL.The threshold values of Vibrio Harvieri,Pseudomonas plecoglossicida,iridovirus and,Cryptocaryon irritans were 250-350,5000-7000,800-1000 and 200-400 copies/μL,respectively.After testing,the upper predicted values of the warning model could basically cover the range of threshold of the pathogens,which will largely help the farming industries foresee the occurring time of diseases and obtain the precious opportunity for prevention.