噻呋酰胺对水稻立枯丝核菌群体的活性变化及其对稻田天敌群落的影响

Shift in activity of thifluzamide against the population of Rhizoctonia solani causing rice sheath blight and its effect on community of natural enemies

分别从未使用过噻呋酰胺及使用噻呋酰胺3年以上的浙江省稻田采集分离立枯丝核菌Rhizoctonia solani,通过监测、分析病原菌群体对噻呋酰胺的敏感性变化,研究了立枯丝核菌对噻呋酰胺的抗药性风险;并以戊唑醇、井冈霉素等纹枯病防治常用药剂为对照,通过田间试验评价了噻呋酰胺油悬浮剂(OD)对稻田天敌群落的影响。结果表明:浙江省未接触过噻呋酰胺的立枯丝核菌群体(n=164)的EC50值分布在0.008~0.135 mg/L之间,且呈近似正态单峰曲线,平均EC50值为(0.073±0.005) mg/L,可作为立枯丝核菌对噻呋酰胺的敏感性基线,用于后续田间抗药性监测。接触过噻呋酰胺3年以上的立枯丝核菌群体(n=130)的EC50值分布在0.009~0.126 mg/L之间,平均EC50值为(0.069±0.080) mg/L,未观察到明显的敏感性下降。对稻田天敌群落影响的田间试验表明,采用12%噻呋酰胺油OD处理7 d后,绍兴稻田的Shannon多样性指数和丰富度指数均显著高于清水对照(CK),而其他时间和地点均与CK无显著性差异。研究表明,采用噻呋酰胺防治水稻纹枯病的田间抗药性风险低,对稻田天敌安全性高。

Isolates of Rhizoctonia solani, the rice sheath blight disease pathogen, were collected from rice fields in different sites before and after the applications of thifluzamide for over 3 years. And the shift of sensitivity to thifluzamide was monitored and analyzed. Meanwhile, the effect of thifluzamide on the community of natural enemies was evaluated by adopt the generally used fungicides,jinggangmycin and tebuconazole, as the pesticide control. It showed that the EC50 value for the population(n=164) of R. solani collected from Zhejiang Province before thifluzamide exposure fitted unimodal distribution and varied from 0.008 to 0.135 mg/L with the mean value of(0.073±0.005) mg/L,which could be adopted as the baseline sensitivity to monitor the sensitivity shift in R. solani. The EC50 value for the population(n=130) which exposed to thifluzamide for more than 3 years varied from 0.009 to 0.126 mg/L with the mean value of(0.069±0.080) mg/L. No obvious sensitivity shift of R. solani to thifluzamide was observed. Field experiments was conducted to evaluate the effect on its natural enemy’s community. The results suggested that both the Shannon diversity index and richness index,7 days after the application of 12% thifluzamide OD in Shaoxing, were significantly higher than those of the CK. While all the above indexes obtained in other time periods or sites had no significant difference with CK. This study indicated that thifluzamide had low risk of field resistance development and is safe to the natural enemy in rice fields.