高屏地區南黃薊馬（Thrips palmi Karny）對殺蟲劑之感受性調查及對第滅寧抗性機制之探討

Toxicity of several insecticides and mechanism associated with deltamethrin resistance in melon thrip (Thrips palmi Karny) collected from Kaohsiung and Pingtung area

"南黃薊馬（Thrips palmi Karny）為臺灣中南部茄子及瓜類作物上之重要害蟲，目前農民主要以殺蟲劑防治南黃薊馬，在長期連續施用藥劑下造成南黃薊馬對藥劑敏感性明顯降低，對合成除蟲菊類藥劑的反應尤其明顯；本研究擬瞭解南黃薊馬對推薦藥劑感受性的現況並探討其對第滅寧之抗性機制。藥劑感受性現況偵測為自高屏地區不同用藥歷史之茄田採集南黃薊馬成蟲，以人工大量繁殖後，取南黃薊馬二齡幼蟲以浸葉法分別測試其對益達胺、覆滅蟎及第滅寧之感受性；生物檢測結果顯示益達胺的藥效佳，覆滅蟎次之，第滅寧最差；南黃薊馬對第滅寧的抗性研究是以泰武地區南黃薊馬為參考品系，結果發現屏東市歸來地區的南黃薊馬對第滅寧原體及成品之抗性比分別大於7.7及17.5倍，旗山地區南黃薊馬對第滅寧成品之抗性比高達16.3倍，顯示歸來及旗山茄田之南黃薊馬已對第滅寧產生抗性。在第滅寧藥液中添加協力劑胡椒基丁醚（piperonyl butoxide, PBO）的生物檢測結果，歸來及海豐兩地區南黃薊馬之協力比超過21.8及18.7倍，顯示南黃薊馬對第滅寧之抗性與氧化酵素（cytochrome P450 monooxygenase, CYP）活性有關。將泰武、海豐及歸來地區採集之南黃薊馬成蟲及幼蟲之RNA，經反轉錄反應（reverse transcription），所得之cDNA以CYP6單氧酶之簡併引子對（degenerate primers）進行PCR反應及電泳分析，結果三個地區南黃薊馬成蟲及幼蟲的電泳圖譜在390 bp處均顯示一明顯條帶，將此條帶定序後確認為CYP6家族中的單一基因序列，暫命名為CYP6-TP；進一步由CYP6-TP基因序列設計專一性引子對，以泰武、海豐及歸來地區之南黃薊馬cDNA為模板進行即時定量PCR（real-time PCR）反應，顯示歸來及海豐地區南黃薊馬成蟲CYP6-TP基因表現量分別比泰武地區高4.63及2.81倍，此結果與生物檢測之抗性比值呈正相關，推測南黃薊馬對第滅寧產生抗性與CYP6-TP基因表現量增加有關。"

"Thrips palmi Karny is the major insect pest on eggplants and melons in central and southern Taiwan where farmers use mainly chemical insecticides to control this thrip. The susceptibility of T. palmi to a number of insecticides, especially pyrethroids, has decreased obviously in recent years under continuous selection pressure. This study intends to measure the toxicity of imidacloprid, formetanate and deltamethrin, using leaf dipping method, to the second-instar larvae of T. palmi obtained from the mass rearing of this thrip collected from eggplant fields with different chemical application history. Imidacloprid displayed the best efficacy, followed by formetanate and deltamethrin. Using T. palmi from Taiwu area as the reference strain, 7.7- and 17.5-fold resistance to technical and commercial grade deltamethrin, respectively, were observed in T. palmi from Gueilai area; and a 16.3-fold resistance to commercial grade deltamethrin was found for T. palmi from Cishan area. The synergism ratios of deltamethrin with piperonyl butoxide, i.e., 21.8 and 18.7 for T. palmi collected from Gueilai and Haifong areas, respectively, suggest the involvement of microsomal cytochrome P450 in its resistance to this pyrethroid. Reversetranscripted cDNA from these three thrip strains were amplified by polymerase chain reaction (PCR) using CYP6 degenerate primers. A single band of 390 bp, observed in the electrophoregrams for all aduts and larvae of T. palmi from the three areas, was confirmed as a member of CYP6 family and subsequently named CYP6-TP. Level of CYP6-TP gene expression in T. palmi was measured by real-time PCR using specific primers for CYP6-TP and cDNA as template. The expression of CYP6-TP gene in T. palmi from Gueilai and Haifong areas were, respectively, 4.63- and 2.81-fold higher than that in thrips from Taiwu area. The results of gene expression were positively correlated with the resistance ratio in bioassay. In conclusion, the deltamethrin resistance developed in T. palmi from Gueilai and Haifong area is closely related to the increased expression of CYP6-TP gene."