Study On The Control Measures, Migration And Damage Of Brown Planthopper Nilaparvata Lugens

Brown planthopper, Nilaparvata lugens is one of the key long-migration insect pests occurring on rice crops, and results in heavy damages on yield production of rice crops in the regions of Yangtze Rive, South China and West China. In this study, the damages caused by N. lugens under different cultivation systems of rice crops were comparatively studied based on the occurrence data of brown planthopper from2000to2008in Wujin District of Changzhou City, simultaneously the effects of meteorological factors on the immigration, fecundity and damage of N. lugens were studied and high efficient insecticides were also selected to control this type of rice planthoppers in combination with different pesticide applications. The results were as following:1. The comparaqtive study was carried out on the rice yields and N. legens damage in different cultivation systems. The results indicated that pant growth was enhanced under high planting density with high levels of nitrogen fertilizers, while the brown planthopper outbreakn was frequently resulted owing to the suitable host plants for N. lugens with high fecundity and better growth and development.2. Through the comparaqtive analysis of the agricultural meteorological factors (including daily temperature, humidity and precipitation) and the systemic occurrence data of N. lugens from2000to2008, one regression formula was established based on6variables significantly correlated with the occurring abundances (Y) of major pestilent generations by the step-by-step regression analysis of DPS system, and its regression accuracy was66.7%. The regression formula is:Y=-436246-997χ1-506χ2-14308χ4+36004χ7-216χ14+1188χ15; whereχ1=the mean humidity in early July, χ2=the daily mean precipitation in middle July, χ4=the mean max temperature in early August, χ7=the mean temperature in August, χ14=the immigration abundances of the1st generation catched by lighttrap, χ15=the immigration abundance of the immigration geration in systemic field.3. Five times of pesticides application were taken to control the occurrences of brown planthopper, N. lugens from2005to2008. The results indicated that the highest activity was found during single low-dose usage of pymetrozine or nitenpyram, showing quicker control efficacy and longer control time. So these two types of new insectcides can be used to replicate some high-toxic pesticides commently applied recently, in addition to improve the eco-agricultural development by reducing the usage of insectcides and finally to accord the concept and demands of green plant protection.4. A series of experiments using same pesticides with different dilution times and dfifferent devices were carried out to control the occurrence of brown planthopper, N. lugens. The results incidated that the more water was added to dilute the pesticides the higher control effectiveness was got, and it was better for the application of mist sprayer relative to small ones to spray same amount of pesticides and water.5. Another experiment using same pesticides during different period was also taken to control the damages caused by brown planthoppers on rice crops. The results showed that the control measures should be taken as well as early in the late stage of paddy crops. And it is the key stage for the rice crops to control the3rd generation and suppress the4th generation at the end of August to the early September (i.e., the rice break period).