番木瓜环斑病流行时间动态分析

TEMPORAL KYNAMICS OF PAPAYA RINGSPOT DISEASE

根据田间和室内试验结果，分析了番木瓜环斑病的季节流行动态、蚜虫田间消长规律以及显症和传染动态。在田间自然状态下，有翅蚜的迁入每年出现３个高峰（６月上旬、８月中旬和１０月中旬）。在蚜虫迁入后的１０～２０ｄ，病害的发展也相应出现高峰，病害的发展与蚜虫的迁入量以及温度、湿度、风速等的变化有关。比较３种数学模型（Ｌｏｇｉｓｔｉｃ、Ｇｏｍｐｅｒｔｚ和Ｗｅｉｂｕｌｌ）对此病流行曲线、显症动态及传染动态的拟合效果，结果前者以Ｇｏｍｐｅｒｔｚ方程为最佳，后两者以Ｗｅｉｂｕｌｌ方程为最优。对流行曲线进行参数分析，推断此病为低毒源量、低速度、长流行期类型，其潜伏期（１１ｄ）比潜育期（１７ｄ）短６ｄ。

Epidemics of papaya ringspot disease (PRV)were monitored in fields in Guangzhou in 1988 and 1989.It was shown by analyzing the data of seasonal dynamics of disease develop-ment that the greatest rate of disease incidence increase appeared in early september.During the epidemic season, alate populations occurred in three peaks:early June,mid-August and mid-October.Ten to twenty days after each peak,there was a peak ofdisease incidence development.The seasonal dynamics of disease development and the growthand decline of the aphid populations were correlated to wind velocity,temperature and hu-midity.By comparing the fitness of three epidemic models (Logistic,Gompetz and Weibull)to the data of disease incidence,it was found that the disease development was best des-cribed by Gompertz model.With the equations of diseae progress,analyzing every parameterand calculating the number of days for disease to reach the incidence of 5%, 50%,90%,and99%,it was found that the disease epidemic pattern of papaya ringspotbelonged to the type of low virus source,low rate of infection and long epidemic pe-riod.By artificial inoculation with aphids(Myzus persicae),two models for infectiousand apparition dynamics of the disease were developped; both of them showed thatWeibull equation best described the dynamic of latent and incubation period,whichwere demonstrated to be about eleven and seventeen days respectively.