Geostatistical Analysis on the Temporal Patterns of the Yellow Rice Borer, Tryporyza incertulas

In order to comprehend temporal pattern of the larvae population of the yellow rice borer, Tryporyza incertulas, and provide valuable information for its forecast model, the data series of the population for each generation and the over-wintered larvae from 1960 to 1990 in Dingcheng District, Changde City, Hunan Province, were analyzed with geostatistics. The data series of total number, the 1st generation, the 3rd generation and the over-wintered larvae year to year displayed rather better autocorrelation and prediction. The data series of generation to generation, the 2nd generation and the 4th generation year to year, however, demonstrated poor autocorrelation, especially for the 4th generation, whose autocorrelation degree was zero. The population dynamics of the yellow rice borer was obviously intermittent. A remarkable cycle of four generations, one year, was observed in the population of generation to generation. Omitting the certain generation or interposing the over-wintered larvae only resulted in a less or slight change of autocorrelation of the whole data series generation to generation. Crop system, food, climate and natural enemies, therefore, played more important roles in regulating the population dynamics than base number of the larvae. The basic techniques of geostatistics applied in analyzing temporal population dynamics were outlined.

Studies on Stimulating Effect of Two Selective Insecticides on the Numbers of Laid Egg by Yellow Rice Borer,Tryporyza incertulas(Walker)and Their Effects on Biochemistry of Rice Plants

Buprofezin and imidacloprid are selective insecticides against Homoptera insects. This paper investigated stimulating effect of the two insecticides on the number of laid eggs by yellow rice borer, Tryporyza incertulas(Walker) of three generations in 20012002. The results showed that the reproductive rate of emergence months during the larvae feeding on the rice plants of Xiushui63 treated with the two insecticides was significantly higher than that of control, indicating that the numbers of laid eggs by the borer was stimulated following buprofezin and imidacloprid applications. However, there was no such effect for the larvae feeding on rice variety Zhendao2 which showed moderate resistance to the insect. In addition, the incidence of stimulating egg laid for the first instar treated with the two insecticides was greater than that for the third instar. Biochemical tests showed that oxalic acid concentration declined, and photosynthetic rate of rice leaves following the two insecticide applications declined significantly compared to control, whereas reducing sugar concentration increased significantly for all other treatments of two varieties except Xiushui63 treated with buprofezin. The level of glutathione-S-transferase varied with rice variety and insecticide.

Damage and economical threshold of yellow stem borer (Tryporyza incertulas) on rice

Systematic measurements to damage and yieldloss due to yellow stem borer (YSB) weremade in the single crop and double crop areasof Hangzhou, Jiaxing, and Huzhou cities,northern Zhejiang Province in 1987-1994. YSBeggmasses were released on rice plants at 0,1, 3, 6, 9, 12 eggmasses per plot (equal to0, 495, 1 500, 3 000, 4 500, and 6 000eggmasses per hectare) from tillering to head-ing. The plot size was 20 m~2. There were 3replications randomly lined. The results in 6locations during 4-6 years of 1987-1994showed that the grain losses caused by eacheggmass at tillering stage was 59.11±2.99 g,elongating 63.18±1.51 g, and heading 74.58

Evaluation and Identification of Resistance to Diseases and Pests for Rice Varieties in Hainan

[Objectives]This study was conducted to select multi-resistant rice varieties in Hainan.[Methods]Seven new rice germplasms were identified by naturally induced disease nursery,field spraying and artificial inoculation.[Results]The restorer line Haihui 1558 was resistant to the dominant races ZB and ZC of rice blast and Tryporyza incertulas,and moderately resistant to pathotype IV of bacterial blight.The restorer line Haihui 227 was resistant to pathotype IV of bacterial blight and T.incertulas.Red rice Hainonghong 1 was resistant to pathotype IV of bacterial blight,and moderately resistant to the dominant races ZB and ZC of rice blast.Black glutinous rice Haifengheinuo 2 was moderately resistant to pathotypes IV of bacterial blight and T.incertulas.[Conclusions]The study provides reference for utilization of rice breeding on resistance to diseases and pests.