(8(2):29-34)MEASUREMENT OF THE DEVELOPMENT OF RESISTANCE TO INSECTICIDES WITH MELON FLY

本試驗乃用瓜斑蠅之成蟲，測定其對合成氯烴藥劑DDT, Toxaphene, Aldrin, Lindane, Ch-lordane及Dieldrin六種，經長期施用後有無抵抗性之現象。 由多次試驗結果得知瓜蠅成蟲對各藥劑之致死量中率(LD50)的藥量(mg/ft2)如下：DDT 50mg/ft2, Toxaphene 30mg/ft2, Aldrin 1mg/ft2, Lindane 1mg/ft2, Chlordane 2mg/ft2及Dieldrin 1.5mg/ft2。 瓜蠅成蟲每世代舉行試驗均用相同的方法及相同的藥量處理，經15世代後，上述六種藥劑對瓜蠅的死亡率均低減，尤其是以DDT更顯著，Chlordane是比較慢的，那就是表示瓜蠅對各種藥劑的抵抗性隨著世代數而增加。 經施用DDT, Lindane及Chlordane三種合成氯烴藥劑處理後之瓜蠅，解剖觀察結果其內部組織形態與施藥後者比較尚無變異。 The purpose of this experiment is to find out the tendency of development of resistance to different insecticides (DDT, Toxaphene, Aidrin, Lindane Chiordane and Dieldrin) with melon fly (Chaetodacus cucurbitae Coq.). Adult melon flies were exposed for 3 hrs. on filter paper with the different insecticides at certain dosage mg/ft2, and found out their LD50. The chemicals tested were DDT 5Omg/ft2, Toxaphene 30mg/ft2, Aidrin lmg/ft2, Lindane lmg/ft, Chiordane 2mg ft2, and Dieldrin 1.5mg/ft2. After testing, the percentage of mortality was recorded and the alive flies were then reared again in the insectary, upon emerged flies from the next generation, they were exposed to the same dosage of the insecticides again, the results of generational changes were listed in the table. According to the test melon flies treated with insecticides showing a tendency of prominent increase of resistance even 15 generations, especially in case of DDT