The Population Dynamics Of Rice Planthopper In Shizong Of Yunnan Province

The rice planthoppers are major pests to rice planting in our country.In the past few years the rice planthoppers happened seriously in Yunnan province.For example the first time seeing the rice planthopper ahead of time,the number of rice planthopper become more and more,in the main days of rice planthopper migrate the number of planthopper is big and it shows many times up with big number of rice planthopper migrate,population grows fast,wide area occurred,the damage is often widespread,serious damage often last for a long time.Shizong is located in northeast Yunnan region des plateaux transition to a low hills and valleys of southeastern Yunnan Area.There are from southwest to northeast direction and southeast to northwest direction corridor.It is the main passageway for white-backed planthopper(Sogatella furcifera,WBPH) migrate in Yunnan from outside and get to GuiZhou,SiChuan,ChongQing in the north. In view of the topography,geographical location,the influence of the monsoon,rice cultivation and the amount of rice planthopper migrate in,Shizong is the most representative area of southeastern Yunnan Region.Study the population dynamics of rice planthopper is very important to the forcasting and prevention of rice planthopper of Yunnan province,even our country.Through compare and analysis the light trapping data of rice planthopper in Shizong of YunNan province in recent ten years,I find that the first time seeing the White-backed Planthopper ahead of time in recent ten years.The results also could be found from the data of Brown Planthopper. When the frequensy of immigration peak were more,the light-trap catches of singele immigration peak were bigger,the light-trap catches would be bigger.Through systematic investigation in Shizong in 2013,the research find that there are 4-5generations of WBPH every year.The white-backed planthopper first seeing time of immigrate in Shizong in mid April.The local farmer raise rice seedlings in the end of March,transplant rice in the mid of May.The first generation after immigrate generation are the major damage generation.The main damage stage are rice tillering stage. The amount of WBPH are more than the amount of BPH.The white-backed planthopper happening mainly from the stage of tillering period to jointing stage.It damage rice most seriously.The brown planthopper happening mainly at filling stage and yellow ripe stage.The number of BPH are far less than WBPH.The damage caused by BPH are also small.Through analysis of variance on data of the number of WBPH to compare the three rice varieties(Ming Liang You529,Feng You Xiang Zhan,Yun Hui 290). The result showed that the significant difference between the number of WBPH on the three rice varieties along the growing periods are all bigger than 0.05.There are no difference with the three rice varieties in the ability of tolerance of WBPH.The reserch compared the control effect on WBPH along imidacloprid, buprofezin, thiamethoxam, chlorpyriphos and pymetrozine.The corrected efficacy of imidacloprid after pesticide apply 30 days and 35 days are-2% and-18%.It shows the number of WBPH rise again after a fall,the persistent bioactivity of imidacloprid are not good enough.The results of corrected efficacy of buprofezin from the time after pesticide apply 15days to 35days are both negative value.Its cure effect are worst.The corrected efficacy of thiamethoxam are-66%,-124%and-26% after pesticide apply 20days,30days,35days.The number of WBPH after the three pesticide apply all rise again,so only apply once can't control WBPH well,we should do the second pesticide apply. The persistent bioactivity of chlorpyriphos and pymetrozine are both well, their control effect are best.