尿素系殺蟲劑二福隆、氟芬隆及諾伐隆於土壤中的消散作用 及其對土壤細菌族群結構的影響

Abstract

本研究探討三種尿素衍生物殺蟲劑：二福隆（diflubenzuron）、氟芬隆（flufenoxuron）及諾伐隆（novaluron）在土壤中的消散，並結合核酸萃取、聚合酶鏈鎖反應（Polymerase Chain Reaction, PCR）及變性梯度凝膠電泳（Denaturing Gradient Gel Electrophoresis, DGGE）等生物技術來瞭解不同濃度藥劑處理下土壤微生物的菌相變化。實驗採用坡堵系與五里林系兩種土壤，分別添加濃度1、10及50 mg/kg的殺蟲劑二福隆、氟芬隆及諾伐隆，定期以HPLC分析土壤中的藥劑殘量，並萃取土壤總DNA後，利用16S rDNA上之泛用引子進行PCR將DNA片段複製放大，再以DGGE電泳觀察施用二福隆、氟芬隆及諾伐隆後各時間點土壤細菌族群結構的變化。實驗結果發現，三種農藥在滅菌土壤中的消散速率均明顯較在未滅菌土壤中緩慢，顯示此三種農藥在土壤中的消散是經由微生物的降解作用。以一級動力方程式計算坡堵系土壤中添加1、10及50 mg/kg二福隆的處理，半衰期依序為3.0、10.1及45.9天，氟芬隆三種起始濃度半衰期依序為75.3、105及433.2天，諾伐隆為27.7、192.5及301.4天，不同藥劑濃度結果顯示，三種殺蟲劑的降解速率皆以高濃度處理者較低濃度處理降解速率較慢。三種農藥的比較又以二福隆的降解速率最快。由PCR-DGGE指紋圖譜發現，添加藥劑後土壤菌相與鮮土菌相不同，坡堵系土中三種農藥以諾伐隆對土壤菌相之影響最明顯，在孵育第119天時與鮮土歧異度最大，為41 %。五里林系土中也以諾伐隆對土壤菌相影響較明顯，在孵育第1天即與鮮土有57 %的歧異度。二福隆及氟芬隆在藥劑降解完畢後，土壤菌相有回復到鮮土菌相的趨勢。

This study is aim to investigate the dissipation of three benzoylurea insecticides in soil, including diflubenzuron, flufenoxuron, and novaluron. The soils used in this study were sampled from Taoyuan District Agricultural Research and Extension Station（Pu）and Hualien District Agricultural Research and Extension Station（Wl）, respectively. Different concentration of insecticides, 1, 10, and 50 mg/kg were applied into the soil. The residues of insecticides in the soil were analyzed with HPLC. The variation of soil bacterial communities during incubation was analyzed with DGGE. It showed that insecticides in sterilized soil have slower dissipation rate than in nonsterilized soil, which strongly imply that insecticide dissipation was caused by microbial degradation. Fitting in first-order equation, half-life of 1, 10, and 50 mg/kg diflubenzuron in soil Pu were 3.0, 10.1, and 45.9 days, respectively; soil treated with flufenoxuron were 75.3, 105, 433.2 days; soil treated with novaluron were 27.7, 192.5, and 301.4 days. Degradation rate was slower as applying 50 mg/kg insecticide than other two concentrations. Degradation rate of diflubenzuron was the fastest among the three insecticides. The DGGE fingerprint showed that after applying insecticides to the soil, bacterial communities was different from the fresh soil. The biodiversity in soil（Pu）community structure to the fresh soil was 41 % as applying 50 mg/kg novaluron into soil, and 57 % as applying 50 mg/kg novaluron to the soil（Wl）.