殺菌劑與殺蟲劑的混合施用對藥劑在土壤中降解之影響

Abstract

藥劑混用間的交互作用可能會影響殺菌劑和殺蟲劑在環境中的持久性，甚至於影響施用環境中的生物性交互作用。本研究針對台灣地區用量較大的殺菌劑和殺蟲劑進行試驗，分別為殺菌劑貝芬替 (Carbendazim, C)、甲基多保淨 (Thiophanate-methyl, T)，以及殺蟲劑馬拉松 (Malathion, M)、加保利 (Carbaryl, A) 和芬化利 (Fenvalerate, F)，探討殺菌劑和殺蟲劑的混合施用對藥劑在土壤中持久性的影響及利用變性梯度凝膠電泳 (Denaturing Gradient Gel Electrophoresis, DGGE) 探討農藥對土壤菌相之影響。本試驗選擇三種土壤進行試驗，分別為Pu, Ta和Wl土壤，探討殺蟲劑的混用對殺菌劑在土壤中之影響，殺菌劑貝芬替在Pu土壤中不同藥劑處理組間降解的差異不明顯；Ta土壤中以混合藥劑的處理組貝芬替在土壤中持久性較長；Wl土壤中貝芬替在試驗初期降解快速，化學性降解作用明顯，然整體降解速率在不同處理間差異不顯著。此外也探討殺菌劑的混用對殺蟲劑在土壤中降解之影響，加保利和芬化利在Pu土壤中之降解以混合藥劑處理組降解較快；Ta土壤中加保利和芬化利在混合藥劑處理下降解較慢，持久性較長；Wl土壤中，加保利和芬化利在混合藥劑處理下降解較快。本試驗也偵測甲基多保淨的代謝與產物貝芬替的生成，結果顯示甲基多保淨的降解量與貝芬替的產生量並沒有達到質量守恆，因此認為甲基多保淨降解可能還有其他無法偵測到的代謝產物。變性梯度凝膠電泳的結果利用Unweighted pair method with arithmetic mean (UPGMA) 將菌相圖譜做聚類分析，結果顯示混合藥劑處理和單一藥劑之菌相結構有差異，可推斷農藥的混合施用會對菌相造成影響，可能為抑制特定的微生物菌群，減緩藥劑在土壤中的降解，或是造成特定可利用試驗藥劑之微生物成為優勢族群而加速藥劑的降解。由以上結果可得知，在土壤中殺菌劑與殺蟲劑的共同存在所產生的相互作用，可能會導致藥劑在土壤中的持久性增長或減短，在不同土壤中影響情形不同，且原因主要來自於混合施用後對土壤菌相造成的衝擊，因此在田間應審慎評估藥劑的混用之影響。

The interaction between pesticides affects the persistence of fungicides and insecticides in the environment, and even the use of the interaction of the soil microorganism. In this study, the effect of mix application of two fungicides, carbendazim and thiophanate-methyl, with three insecticides, malathion, carbaryl and fenvalerate on persistent of these pesticides on soil was investigated. Meanwhile,the impact of soil communities was also monitored. From the result, the carbendazim degradation rate is not significantly different between single and mixed treatments in Pu and Wl soil. In Ta soil, the carbemdazim mixed treatment degraded more slowly than single treatment. In addition, the study also investigate the mixed fungicides pesticides in soil degradation on the impact of insecticides in soil degradation. In Pu soil, the carbaryl and fenvalerate degradation rate increased in mixed treatments. In Ta soil, the carbaryl and fenvalerate mixed treatment degraded more slowly than single treatment. In Wl soil, the carbaryl and fenvalerate degradation rate is not significantly different between single and mixed treatments. The thiophanate-methyl metabolite carbendazim was detected. The metabolites produced amount weren’t equal to the thiophanate-methyl degraded amount.The result indicated that thiophanate-methyl may degrade to other metabolites in experimental period. The DGGE fingerprint and cluster analysis result indicated that pesticide mixed treatment may create the impact on soil community. The impact on bacterial community may inhabit the degradation of pesticides and therefore influence the persistenc of pesticides in environment. Thus there are assessment when appling fungicides with insecticides simultaneously in soils.