Influence Of Adverse Environmental Factors On Two Biotypes Of Rice Brown Planthopper And Analysis On The Risk Forecasting Of Rice Resistant Varieties To The Pest

In this thesis, the variation dynamics of rice brown planthopper (BPH) , Nilaparvata lugens (Stal) biotypes in some main rice regions in China was monitored. The BPH biotype II and biotype Bangladesh were used as the study object, the influence of various BPH biotypes composing proportions on the resistance of rice varieties was studied;the variation trend and speed of biotype Bangladesh under the intimidation of resistant varieties was analysed;the tolerance of various BPH biotypes to adverse environmental factors,such as high temperature, starvation,soaking in water and insecticide were studied. Based on the above results,the venture of the resistant varieties to BPH biotype II and biotype Bangladesh was forecasted.The main results were as follows:(l)The result of monitoring on the biotypes of BPH collected from some main rice regions in china indicated that the dominant biotype of the BPH collected from Simao,Yunnan, belonged to biotype Bangladesh, The dominant biotype of the BPH collected from the other collecting locations belonged to biotype II .The proportion of BPH biotype Bangladesh was from 24.0% to 46.67% in Nanning,Guangxi;that was from 4.35% to 26.67%, from 6.67% to 8.33%, from 11.43% to 14.29% in Kuaiyuan,Yunnan and Xinyang,Henan and Jiangpu,Jiangsu, respectively.(2) The influence of various composing proportions of rice brown planthopper biotype II and biotype Bangladesh on the resistance of rice varieties was studied by using the rotational composite design of quadratic regression. The result indicated that IR₃₆ would become susceptible when the proportion of biotype Bangladesh was 69.40% and that of biotype II was...