Epidemiologic Study Of Silkworm Pebrine Disease In Guang Xi Province

Silkworm pebrine is a serious disease and an important quarantine object for sericulture.The number of silkworm eggs that will be eliminated is mainly based on the samples infected.So,the occurrence,control and forecasting of silkworm pebrine disease have attracted attention of research institution and silkworm egg-producingfarm.The microsporidia is the pathogen of silkworm pebrine disease and it is mainly transmitted through embryo and per oral infection.The microsporidia from insect such as cabbage butterfly,mulberry geometrid,gold tail moth,parocneria orienta and mulberry pyralid have been reported to infect silkworms.So the forecasting of pebrine disease through survey of pest situation is very difficult.Since the insect growth,development and pathogen activity are significantly affected by the meteorological factors,it is possible to forecastsilkworm pebrine disease through analysis of the relationship between microsporidia and meteorological factors.Based on the pebrine quanrantine data of state-owned silkworm eggs producing farms,this paper analyze the relationship between geographical location,season and the pebrine disease and achieved the hot spot of disease incidence.Our results showed that the incidence of pebrine disease decreased gradually between 1994 and 2014.The incidence of pebrine disease in northwestern Guangxi is the lowest and that in northeastern part is the highest.The incidence in spring is higher than that in autumn in southern and southeastern Guangxi;incidence in the autumn in central Guangxi,northwestern Guangxi and northeastern Guangxi is higher than that in spring.The time of the high incidence of pebrine disease varied between the different parts of Guangxi province.And southern Guangxi is the hottest spot of pebrine disease incidence.We collected the incidence of pebrine disease and meteorological factors from silkworm eggs producing farm A,which is a hot spot of pebrine disease incidence.We analyze the relationship and constructed stepwise regression model between meteorological factors and the incidence of pebrine disease.And correlation analysis,partial correlation analysis and path analysis were further performed and the key meteorological factors that affected the incidence of pebrine disease was determined.The stepwise regression model for spring was:y=432.48998-9.05952X₁-6.05868X₃+13.65437X₅+15.95724X₆-30.8456X₇+0.66849X₁₀-0.15036X₁₄+1.09316X₁₇-0.40647X₁₈-0.64209X₁₉.the average forecasting accuracy of stepwise model is 80.82%.The forecasting accuracy of the incidence of pebrine disease in spring is 98.50%.The models showed that the temperature is the major factors and the light intensity and rainfall were in the next place.The average temperature of June is of most importance.Theregressionmodelforautumnisy=520.99469-20.30274X₃-63.69031X₄+55.66015X₅+9.72061X₇+0.29532X₈-0.22553X₉-0.14123X₁₃+0.81695X₁₅+0.67996X ₁₈.The average forecasting accuracy is 82.82%.In 2015,the forecasting accuracy is 88.38%.the models showed that the major factor is temperature and the rainfall and light intensity is next.The positive effect of the temperature in September is significant and the negative effect of temperature in August is also important.