共生菌在褐飞虱致害性变化中的作用

研究了不同虫源和致害性褐飞虱Nilaparvata lugens种群体内共生菌数量动态及其对褐飞虱在抗虫品种上的取食选择、生长发育、繁殖以及氨基酸转移酶活性的影响。结果表明，褐飞虱田间种群的致害性与其体内共生菌数量有关。广西南宁种群雌成虫体内的共生菌数量显著地高于浙江杭州和龙游两个虫源的雌成虫体内共生菌数量，而已纯化的3个不同致害性生物型体内的共生菌数量无显著差异。取食抗性品种能显著减少生物型Ⅰ雌成虫体内的共生菌数量。缺乏共生菌时，生物型Ⅰ、Ⅱ若虫对水稻品种TN1和ASD7的选择性增大，而对Mudgo的取食选择性下降。尽管缺共生菌的3个生物型在已适应的和不适应的感虫和抗虫品种上的若虫存活率和雌成虫产卵量均下降，若虫历期明显延长，但在已适应品种上的变化程度明显小于在不适应的抗虫品种上的变化程度。共生菌还明显影响成虫体内丙氨酸氨基转移酶和天门冬氨酸氨基转移酶的活性。这些结果证明体内共生菌的数量和质量在褐飞虱对水稻致害性的变化中发挥了重要作用。

Role of endosymbiote in virulence change of the brown planthopper to rice resistant varieties

Dynamics of the symbiote was monitored in different geographic and virulent populations of the brown planthopper (BPH), Nilaparvata lugens Stal, to determine its role in nymphal feeding selection, development and adult reproduction.Effect of symbiote on the activity of transaminases in BPH feeding on different resistant rice varieties was also examined. The results showed that the virulence of BPH to rice resistant varieties was closely related to number of the symbiote in BPH from the paddy fields, and abundance of the symbiote in BPH from Guangxi Province was markedly greater than that from Hangzhou and Longyou in Zhejiang Province, while no obvious differences in numerical dynamics of the symbiote were found among the three purified populations with different virulence to the resistant varieties (biotype Ⅰ, Ⅱ and Ⅲ) from the greenhouse in International Rice Research Institute (IRRI). Number of the symbiote reduced significantly in female adult of BPH biotype Ⅰ on resistant rice varieties IR26, Mudgo and ASD7 compared with that on susceptible rice variety TN1. The aposymbiotic nymph of biotype Ⅰ and Ⅱ treated by high temperature in egg stage preferred TN1 and ASD7 to Mudgo. The markedly lower nymphal survival rate, adult fecundity and activities of alanine transaminase and aspartic transminase, and longer nymphal duration were recorded in the three aposymbiotic biotypes than in control ones on susceptible and resistant rice varieties, however, the much greater changes occurred in the three tested biotypes when they fed on inadaptable resistant rice varieties. These results implied that the symbiote should play an important role in change of virulence of BPH population to resistant rice varieties.