(35(1):107-117)小菜蛾抗藥性之研究－VII. 防治藥劑之作用特性及受抗藥性之影響

Both the initial and residual activities of 18 organophosphorus insecticides, 5 synthetic pyrethroids, 2 carbamates and 2 tertiary amines on the diamondback moth, Plutella xylostella (L.) were determined. All the synthetic pyrethroids exhibited good initial activities but followed with poor residual effects. Two tertiary amines and carbofuran have similar residual activities except the strengths were different. Methomyl showed no initial action as well as residual effect. The organophosphorus insecticides were the largest chemical group subjected to the test and they demonstrated various action patterns. Some of them showed high initial and residual activities but others were not. The impacts of insecticide resistance on the effect of insecticides were also measured. Once the insecticide efficacy was affected by resistance, the activity profile was lowered and shortened. The prothiophos-selected resistant DBM strain was used to check the validity of the testing method and the result was satisfactory as the test indeed pinpoint the prothiophos-resistance is the origin of resistance. This testing method was also carried out on the field-collected DBMs from different geographic origins to clarify their insecticide resistance characteristics. 本研究檢定目前登記用於防治小菜蛾，Plutella xylostella (L.)，殺蟲劑對本省感性品系宜蘭小菜蛾之初效及殘效。結果發現合成除蟲菊精類之作用均一致，在現有推廣濃度下，僅有良好的初效而殘效則不足，因此如蟲體未被藥液施及，僅靠乾涸於葉表面之藥膜使小菜蛾中毒的機會極低。18種供試的有機磷藥劑對小菜蛾之毒效因藥劑而不同，並且差別極顯著。初效以美文松、賽達松、佈飛松、減大松及普硫松等最好；亞特松、施力松、達馬松及美福松則次之；巴拉松效果雖佳，但非蔬菜用藥。殘效方面以美福松最長，達馬松、施力松及普硫松次之，美文松、二氯松及乃力松均可謂無殘效。有機氮及氨基甲酸鹽類中，培丹及硫賜安之初效及殘效均佳，加保扶初效和殘效則屬中等。 抗藥性會使小菜蛾之初效反應下降，殘效反應縮短。測得之結果顯示，抗合成除蟲菊精劑之反應在感性及抗性品系小菜蛾頗一致，但抗有機磷之特性則隨藥劑之種類而有變化，一般而言，初效佳及致毒作用快者所受之影響較小，如美文松及賽達松。 同時亦探討利用本試驗之方法，即在網室以商品級農藥噴施推薦濃度之藥液於菜苗後接蟲測定毒效，檢定田間抗性小菜蛾之抗性特質，以選取防治該抗性品系之最佳藥劑。發現以室內經普硫松汰選之抗性小菜蛾供試時，可成功地測出該品系之（1）抗普硫松特性及（2）對數種其他有機磷之交互抗性。若以採自馬祖，對農藥抗性較單純之小菜蛾供試時，則可測出較本省西海岸各抗藥品系小菜蛾更為敏感之農藥感受性。再以（1）室內汰選之抗普硫松品系，（2）二個馬祖品系及（3）四個本省抗藥品系比較對13種常用殺蟲劑之感受性時，各品系之總體表現與其來源極為符合，故此一測試方法確實可作為鑑定未知抗性特質之田間小菜蛾品系之用