二代白背飞虱对粳稻为害损失及其防治指标研究

通过接虫笼罩法，研究了二代白背飞虱在武育粳三号上的增殖规律，为害损失及防治指标。结果表明，不同水稻生育期，不同虫口密度的白背飞虱的增长速度不一样，同一生育期，低密度的增殖速度要大于高密度，但总虫量高密度处理显著高于低密度区。二代白背飞虱百丛虫量与水稻产量损失呈极显著正相关（ｒ＝０．９７６１），关系式为Ｙ＝１４．２５０３ｌｇ（Ｘ）－２９．０９５５（Ｘ为７月１９日白背飞虱百丛虫量），防治指标为１８０￣

ECONOMIC DAMAGE TO JAPONICA RICE BY THE SECOND GENERATION POPULATION OF THE WHITE-BACKED PLANTHOPPER

A field trial was performed to estimate the damage to Japonica rice( Wuyu-geng 3) by the second-generation population of the white-backed planthopper, Sogatella furcifera( Horvath) , and the economic threshold for the pest. Infestation was established in caged rice field plots (10 hills per plot) at the densities of 200,400,800,1600 and 2400 nymphs (1st or 2nd instar) per 100 hills with 3 replications. Three plots without infestation were sprayed with the insecticide buprofezin and used as control treatment. The results showed that the increase of the population differed among the treatment with varying levels of initial infestation. Higher reproductive potential was observed in the treatments with lower levels of infestation though the density was eventually greater in the plots infested at higher densities. The yield loss was significantly correlated with the population density: (Y = 14. 2503 lg(X) -29. 0955, r = 0. 9761**) . The economic threshold was thus estimated to be 180 - 190 planthoppers per 100 hills. This suggests that spray is needed when the second-generation population infests the crop earlier at a medium level.