Study On Resistance Of New Rice Resistent Varieties (Lines) To Nilaparvata Lugens (Stal) And Adaptability Changes Of Nilaparvata Lugens (Stal)

The brown planthopper, Nilaparvata lugens (Stal) is a serious pest of rice, which threats to rice production. Host-plant resistance is the most effective and environment friendly approach to control the damage caused by insects. Evaluating the resistance of rice varieties (lines) with by comprehensive identification methods, then screening out sereral rice materials (carring Bph15or Bph14and Bph15) with higher resistence to brown planthopper and high yield. The ralationship between resistence and chemical content in three resistant lines MH63, MH63(Bph15) and MH63(Bphl4+15) was studied by determining the content of nutrition and oxalic acid. It is necessary to construct the Ife table of BPH and study the influence of rice materials on biological parameters. Thus, adaptability Changes of Nilaparvata lugens (Stal) to resistant lines can be revealed. Results are as follow:1. The resistance of16rice varieties (lines) to the brown planthopper (BPH), Nilaparvata Lugens (Stal) was evaluated using a modified bulk seeding test, honeydew measurement during tillerring stage, evaluation of the resistance of adult plants in the field,assessment of duild dominance in the arthropod community and rice yield. The results indicate that12varieties (lines) were highly resistant to BPH and2lines were moderately resistant to BPH at the seedling stage. In comparation with the contrast TNI, there were significant differences in honeydew production and accumulated planthopper in the field of14resistant varieties (lines). Besides improved resistance, the aboundance of phytophage were lower, aboundance of parasitoids and predators were higher with more stable arthropod community structure.5resistent varieties (lines) Guangzhang63-3S/Huahui15, Guangliangyoul06, Y58S/Hual5, Guangliangyou476and Guangzhan63-4S/Huahuil5with higher yield were required for further research and extensive application.2. To clarify resistence and its mechanisms of rice varieties (lines) to brown planthopper, antixenosis and antibiosis of rice materials to BPH were tested. The results demonstrate that rice resistant lines have obvious antibiosis and antixenosis. The number of nymphs on rice lines MH63(Bph15) and MH63(Bphl4+15) decreased significantly by49.03%and60.33%after releasing for eight hours respectively, compared with the control MH63.24-h later, the number of nymphs on the control was2.06and2.58times than MH63(Bph15) and MH63(Bph14+15) separately. Which stands for that two rice resistent materials had obvious antixenosis to BPH. Antibiosis scores were60.71%and 58.61%on the MH63(Bph15) and MH63(Bph14+15) respectively. Lower survival rate landed on rice lines MH63(BphlS) and MH63(Bph14+15) means that rice resistant lines have significant antibiosis.3.There were close correlation between the content of soluble sugar, starch, total free amino acids, soluble proteins, oxalic acid and resistance to BPH. The results show that relationship between resistance and starch, total free amino acids is negative, however, positive correlation with oxalic acid content. The content of soluble starch, on MH63(Bph15) and MH63(Bph14+15) was45.86%and55.45%lower than the contrast respectively. Total free amino acids was21.87%and36.30%less than MH63on MH63(BphlS) and MH63(Bph14+15) separately. Howerer, the amount of oxalic acid on MH63(Bph15) and MH63(Bph14+15) was64.99%and58.93%more than the control.4.To investigate adapatibility changes of BPH on rice resistant varieties (lines), biological parameters of BPH were studied in this paper. After seven generations rearing on MH63(Bph15) and MH63(Bph14+15), no evident differences have been identified in some biological parameters of BPH between resistant lines and contrast. Howerer, fecundity of female, population trend index and relative fitness were still obviously lower than MH63.4.1Compared with the contrast, development duration was significantly prolonged and weight was lightened of the first genetation BPH on resistant varieties. The weight of BPH lightened45.76%and49.15%for females,45.58%and51.02%for males on MH63(Bph15) and MH63(Bph14+15), respectively. The development duration of BPH prolonged37.11%and27.78%on MH63(Bph15),80.23%and55.93%cn MH63(Bph14+15). No obvious effects have been identified on weight of female and development duration of male after feeding seven generations on MH63(Bph14+15).4.2The survival rate from3rd to5th instar on MH63(Bph15) and MH63(Bph14+15) in Gl generation were11.22%and37.78%lower than the contrast. The adult emergence rate on MH63(Bph15) and MH63(Bph14+15) were67.82%and35.58%,30.08%and63.32%lower than MH63, respectively. After seven generations rearing on resistant lines, there were no apparent effects on survival rate of nymph, emergence rate, female rate, copulation rate, hatchability for MH63(Bph14+15), emergence rate, female rate, copulation rate, hatchability for MH63(Bph14+15). 4.3The fecundity of female on MH63(Bph15) and MH63(Bphl4+15) were80.90%and88.73%in G1generation,48.79%and72.49%in G7generation less than the MH63. After seven generations rearing on resistant lines, fecundity of female was still obviously less than MH63, which stands for that a stronger inhibition of ovipositing have been discovered on MH63(Bph15) and MH63(Bph14+15). The study indicated that population trend index and relative fitness were still obviously lower than MH63. After seven generations rearing on MH63(Bph15) and MH63(Bph14+15), population trend index were61.22%and76.67%lower than the control, relative fitness were61%and77%lower than the MH63separately.