地上部植食者褐飞虱对不同水稻品种土壤线虫群落的影响

地上和地下部生物群落的交互作用对于调控陆地生态过程具有重要作用。在盆栽条件下利用2×2析因设计研究了褐飞虱(Nilaparvata lugens)取食不同水稻品种后对土壤线虫群落的影响。结果表明, 褐飞虱侵害水稻9 d后, 感虫品种(广四和汕优63)的土壤线虫总数、属数及自生线虫(食细菌线虫、食真菌线虫和捕食性线虫)数量增加, 并且一般达到显著水平(P<0.05); 而上述指标在抗虫品种(汕优559和IR36)土壤中则呈现相反的趋势。植食性线虫数量在强感虫品种广四上显著增加(P<0.05), 而在强抗虫品种IR36上显著减少(P<0.05)。褐飞虱和水稻品种对土壤线虫的生态指数(线虫通道指数、Shannon-Wiener指数、成熟度指数、富集指数和结构指数)没有明显影响, 可能与供试土壤线虫群落组成单一及褐飞虱作用时间较短有关。总之, 褐飞虱强烈影响土壤线虫数量、群落组成和营养结构, 并且作用的方向(促进或抑制)和程度依赖于水稻的品种特性, 揭示出地上部植食者的短期侵害将对稻田土壤生态系统的结构和功能产生深远影响。

Aboveground herbivory by the brown planthopper(Nilaparvata lugens)affects soil nematode communities under different rice varieties

Interactions between aboveground-belowground communities play an important role in regulating terrestrial ecological processes; however, the interactions between rice varieties, herbivory and the soil community are often ignored. A pot experiment with a full 2×2 factorial design was conducted to examine the impacts of the brown planthopper (Nilaparvata lugens) and rice variety (susceptible or resistant) on the soil nematode community. The results showed that, after nine days, aboveground herbivory significantly (P<0.05) increased total abundance, numbers of nematode genera and the number of free-living nematodes (such as bacterivores, fungivores, and predators), under the rice varieties susceptible to the brown planthopper (Guangsi and Shanyou63), whereas an opposite trend was observed under the rice varieties resistant to the brown planthopper (Shanyou559 and IR36). In the presence of planthoppers, herbivorous nematodes significantly increased under the most susceptible rice variety Guangsi but significantly decreased under the most resistant rice variety IR36. Both planthopper and rice variety had negligible influences on ecological indices of the soil nematode community, including nematode channel ratio (NCR), Shannon-Wiener index (H'), maturity index (MI), enrichment index (El) and structure index (SI). This might be due to domination by bacterivores of the soil nematode community and the short length of exposure to aboveground herbivory for our pot experiment (only nine days). In conclusion, the brown planthopper strongly affects the abundance, composition as well as trophic structure of nematode community, but the direction (i.e. stimulation or depression) and magnitude of influences interacts with the rice variety. Our results imply that short-term aboveground herbivory may impose profound impacts on the structure and functions of rice paddy ecosystem.