| Sorghum is one of the fifth most widely grown cereal crops in the world,and is one of the most important cereal crops in China.Sorghum Aphid can seriously affect the yield of sorghum and is very destructive.With the popularization of sorghum and the expansion of planting area,the problem of Sorghum Yield loss caused by aphid damage is becoming more and more serious.On the basis of summarizing the research status of domestic and overseas research on the aphid of sorghum and sorghum,this paper systematically investigated the population dynamics of Forage Sorghum in Gansu,Lanzhou.Two methods were used to identify the aphid resistance of 14 Forage Sorghum Varieties,the life table of Schhizaphid graminum(Rondani)under different temperature1.Evaluation of aphid resistance of 14 Forage Sorghum Varieties To clarify the aphid resistance characteristics in different types of forage sorghum varieties.Under the condition of the natural field and the mix aphid population(Rhpalosiphum padi(L),Sitobion avenae(Febricius)and Schhizaphid graminum(Rondani))as the test pests.The aphid number ratio method and the aphid damage index were used to identify and analyze the field resistance to aphid in 14 forage sorghum varieties.The aphid damage index results show that,jujia(17.78),3180(15.56),Mule 8000(16.67)and Big kahuna(18.89)were moderate resistance,except for the difference between the 3180 and the other 4 varieties,it was significantly lower than other varieties;Liaotian No.3(21.11)and 2180(25.56)were low resistance;Japannese forage sorghum(32.22),Hercules(33.33),Liaotian No.5(35.56),1990(35.56)and 4180(38.89)were low infection,1230(46.67)and 1180(45.56)were moderate infection,and Paka(57.78)was high infection,significantly higher than other varieties.2.Population dynamics of mixaphids population in field of Forage Sorghum in Lanzhou In order to clarify the occurrence and distribution of mix aphid population inLanzhou Gansu.From May 2016 to October 2016,the quantitative dynamics of aphids in different fields were recorded by means of fixed point and fixed plant.The spatial dynamics of the aphid population were analyzed by using the diffusion coefficient method,the negative two distribution K value method,the C value method and the mean crowding degree method.The results showed that the mix aphid population in Lanzhou Forage Sorghum Planting experiment area occurred in the growth stages of Sorghum in Gansu.The 2016 survey data show that Rhopalosiphum padi(L)in forage Sorghum before mature period was the dominant species,the highest was 5096 per plant.The Schizaphis graminum(Rondani)was the dominant species in the flowering stage,and the highest was 2435.In the field of foragesorghum,the population of mix aphid population was aggregated,and the degree of aggregation showed the trend of diffusion aggregation and diffusion.3.Life table of Schhizaphid graminum(Rondani)under different temperature To determine the effect of temperature on the growth and development of Schhizaphid graminum(Rondani).The life parameters of Schhizaphid graminum(Rondani)were studied by using life table technique in the artificial climate chamber in the laboratory,which was set at 16L:8D,at the temperature of 15?,20?and 25?.The results showed that the net reproductive rate(R0)of the Schizaphis graminum was the highest at the temperature of 25?,was 20.783.The lowest in the temperature of 15? was only 18.197.The average generation period(T)was 13.115 at the time of 25 ?,and was the longest at the time of 15 ?,which was about 20.092.The finite rate of increase(?)and intrinsic rate of increase(rm)of the Schhizaphid graminum(Rondani)were highest at the temperature of 25?.Respectively,with the temperature increasing,which was about 0.231 and 1.260.The population doubling time(T)in 25? is 2.157 d. |
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