The Effect Of Elevated Carbon Dioxide On Laodelphax Striatellus Gaining, Bring Virus And Population Dynamics

In recent years, rice stripe virus (RSV) spread by the small brown planthopper (Laodelphax striatellu Fallen) does great damage to rice production of China, which is raging in the middle and lower reaches of Changjiang River these years. The occurrence scope and damage degree of the virus, one of the most destructive rice diseases in Changjiang-Huaihe Area rice belt, are enlarging year by year after coming of 21 century. With development of economy, the gain speed of greenhouse gases concentration, with CO2 as the center, becomes greater obviously. CO2 concentration has increased from 265μl/L in the beginning period of Industrial Revolution of 19th century to 370μl/L nowadays according to the survey and evaluation result. This paper researches into the influence on Laodelphax striatellu gaining, bringing and population dynamics, under simulated condition of increasing CO2 concentration. Through measuring virus'species characters, rate and amount of virus and its influence on rice nutrition, this paper further explains prevalent organism of stripe virus disease's outbreak, which is the theoretical basis of controlling this virus.Through simulating CO2 concentration by the way of gas cell, this paper researched into population growth of Laodelphax striatellu under the condition of 370ppm,470ppm,570ppm. The results showed that with the increase of CO2 concentration, the first two Laodelphax striatell generations'death rate won't change obviously, while the more the generations are, the lower the death rate becomes. When there're more generations, Laodelphax striatellu species trend indexes become larger, which indicates Laodelphax striatellu species tend to increase no matter in high or low concentration, especially the fact that index reaches highest under the condition of 570ppm shows CO2 high concentration may affect increase of Laodelphax striatellu for a long time.Through DIBA to measure virus rate of Laodelphax striatellu with different CO2 concentration and different generations, the result manifested the Laodelphax striatellu bring more virus with the increase of generations; in the meanwhile, under high concentration(470ppm and 570ppm), virus rate of the third generation gains 55.8% and 39.1% increase than the first one respectively, which shows with the increase of the CO2 concentration in the future, trend of RSV spread by Laodelphax striatellu will be upwards.According to the conservative domains of the sequences from Rice stripe virus(RSV) in GenBank, a pair of specific Real Time-PCR primers were designed and used for quantitive detection of RSV. The RNA which purified from Laodelphax striatellus uncultivated with CO2 was reverse transcripted to cDNA and the cDNA was used for standard preparation. The standard curve was established by diluting the standard preparation with 5 times multiproportion. The results of Real Time-PCR indicated that the content of RSV in Laodelphax striatellus cultivated with different density of CO2 was different. the content of RSV was highest in 470ppm CO2 and that was lower in 570ppm, while that was lowest in 370ppm. This finding reveals that changing the density of CO2 may make a different in replication of RSV in Laodelphax striatellus and 470ppm CO2 is best suitable for replication of RSV.The increase of CO2 concentration can promote photosynthesis of host plan, increase carbohydrate in the organism, lessen nitrogen content, or even change content and formation of histidine. Therefore, we tested soluble saccharide, soluble protein, FAA and starch content in the rice under different CO2 concentration. From the result we can see in high CO2 concentration condition, soluble saccharide, FAA and starch content increase by 45%,30%,1.17% respectively, while soluble protein decreases by 12%, which was good for Laodelphax striatellu from the aspects of getting food and breeding. Four days'observation showed that ivability of nymphae of Laodelphax striatellu decreases by 8.79% under the condition of 570ppm, which was good for the development of its species and worsen virus'spreading in contrast to decrease of 11.81% and 14.06% in conditions of 470ppm and 370ppm respectively. So with the increase of CO2 concentration around the globe, Laodelphax striatell will bring more harm.