Effects Of Bacterial Blight On The Interactions Of Rice-Nilaparvata Lugens(st?l)-Anagrus Nilaparvatae In Different Nitrogen

In the rice field ecosystem,rice is affected by the pathogen and herbivore during its growth development.The occurrence of these two facors is not independent,the outbreak of rice bacterial blight,brown planthopper and its natural enemy have direct or indirect interaction.Our previous research also found that rice bacterial blight infection affect the behavior of brown planthopper and its natural enemy Cyrtorhinus lividipennis.However,interactions between disease and plant and insect can be affected by other abiotic or biological factors in complex ecosystems.As an important non-biological factor,nitrogen fertilizer has a significant impact on the occurrence of crop diseases or pests.However,it is not very clear whether nitrogen fertilizer will affect disease,plant and insect interactions.Therefore,the study use bacterial blight,an important rice disease,and Nilaparvata lugens(St?l),an important rice pest,and its natural enemy,Anagrus nilaparvatae as research objects,analyzing the interactions between rice bacterial blight and rice,brown planthopper,and Anagrus nilaparvatae under different nitrogen levels(low nitrogen: no nitrogen fertilizer;medium nitrogen: 90kg/ha;high nitrogen: 180 kg/ha).In order to lay a theoretical foundation for the understanding of the interaction between rice and brown planthopper and its natural enemies in complex ecosystems.The main results are as follows:1.The occurrence of rice bacterial blight in different nitrogen levels.With the prolonged time of disease,the relative area of bacterial leaf blight increased.Observed on the flag leaf of susceptible rice: after 3 days infection,the low-nitrogen rice can show typical symptoms such as water-stained lesions and yellowing of the leaf margins.After 10 days infection,the whole leaf is scorched and the leaf is yellow.The medium-nitrogen rice began to develop after 3 days onset of disease,and the onset was significant after 5 days infection.Dark green spots appeared,and the tip and leaf margins were yellow.The high-nitrogen rice had a slower onset,no difference between the infected and healthy leaves after 5 daysinfection.Significantly,symptoms such as yellowish curly leaves appeared after 10 days infection.There was no significant difference in the plant height and root length of infected rice,but a series of unfavorable rice growth phenomena occurred,such as lower leaf chlorophyll content and lower nitrogen accumulation in plants.2.Oviposition and developmental duration of BPH after rice bacterial blight infection in different nitrogen levels.In different nitrogen levels,there was no significant difference in the oviposition,hatching rate,and nymph developmental duration of BPH on 5 days infected rice and healthy rice.The effect of bacterial blight on the content of free amino acids in the phloem of rice was different in different nitrogen levels.The contents of Glycine(Gly)and Aspartic acid(Asp)were significantly lower in low-nitrogen 10 days infected rice.After 3days infection,the content of aspartic acid(Asp)was significantly higher than healthy rice in medium-nitrogen levels and the content of phenylalanine(Phe)was significantly lower in healthy rice than 10 days infected rice.The content of leucine(Leu)was significantly higher than that of healthy rice after 5d infection,and the content of phenylalanine(Phe)was significantly lower than 10 days healthy rice.3.Effects of different nitrogen and rice bacterial blight on host location behavior of BPHThrough H-tube we can see that the effect on the selection of BPH after rice bacterial blight at different time in different nitrogen levels was different.BPH had a tendency to choose 3days-infected rice and after 5 days and 10 days infection BPH had a tendency to choose healthy rice.BPH significantly tended to be selective when it was 5 days and 10 days.When low-nitrogen rice was sensitive to 3 days disease,BPH had a tendency to choose susceptible rice,and after 5 days and 10 days infection,BPH tend to choose healthy rice.When nitrogen were high,BPH significantly tended to be selective when it was 5 days and 10 days.The volatile components of rice and the healthy rice in the same period in different nitrogen levels were detected by GC/MS.There were significant differences in the contents of six kinds of volatiles between infected rice and healthyrice,mainly terpenes and alkanes.Among them,the content of ?-Pinene and Camphene were significantly increased in infected rice,showing a strong regularity.Under the condition of medium-nitrogen and high-nitrogen,the infected rice contains ?-Pinene,Camphene,Tridecane,Hexadecane and other volatiles are significantly higher than that of healthy rice..Effects of different nitrogen and rice bacterial blight on host location behavior of A.nilaparvatae.Different nitrogen levels and the occurrence time of bacterial leaf blight,have an effect on BPH natural enemy A.nilaparvatae.In the medium-nitrogen and high-nitrogen at 5 days and 10 days,A.nilaparvatae.had a tendency to choose infected rice induced by BPH.There are 49 varieties of rice volatiles induced by BPH after 24 h were identified by GC-MS.?-Pinene,Monterpene,Propanoic acid(2-methyl-),?-Cedrene,Heptadecane and Cedrol are significantly different between infected and healthy rice.Among them,?-Pinene,Monterpene,Propanoic acid(2-methyl-),and ?-Cedrene were found in medium-nitrogen infected rice at 5 days and 10 days.The content of?-Cedrene and Heptadecane in infected rice was significantly higher than healthy rice.In high-nitrogen rice,?-Pinene,Monterpene and ?-Cedrene were significantly higher than healthy rice at 5 days and 10 days.