東方果實蠅對馬拉松的生化抗性機制探討

Biochemical mechanisms of malathion resistance in oriental fruit fly (Bactrocera dorsalis)

東方果實蠅（Bactrocera dorsalis (Hendel)）是國內最重要的果樹害蟲之一，施用殺蟲劑是目前最主要的防治方法，而馬拉松是最早於田間防治東方果實蠅的殺蟲劑之一。利用室內累代篩選的馬拉松抗性品系和感性品系做比較，探討四種生化抗性機制（酯酶、麩胺基硫轉移酶、多功能氧化酶及標的不敏感性-乙醯膽鹼酯酶）在馬拉松抗性上的貢獻，其結果顯示，除麩胺基硫轉移酶沒有差異存在外，其餘三種酵素活性都有顯著差異。其中抗性蟲的酯酶及多功能氧化酶活性較高；而感性蟲其乙醯膽鹼酯酶的活性較高。此外，利用四種不同的抑制劑（馬拉松、馬拉松氧化態、乙基巴拉松氧化態及撲滅松氧化態）探討乙醯膽鹼酯酶的不敏感性，其結果顯示，抗性蟲其乙醯膽鹼酯酶對抑制劑較不敏感，其半數抑制濃度較高，和感性蟲有6倍以上的差異。進一步探討酯酶的酵素動力學顯示，馬拉松抗性蟲其酯酶活性的變化是來自於量的增加而非性質的改變。綜合上述，東方果實蠅會對馬拉松產生抗性的主要機制包括酯酶量的增加、多功能氧化酶活性的增加及乙醯膽鹼酯酶對抑制劑的不敏感性等三種生化機制所造成的。

"The oriental fruit fly, Bactrocera dorsalis（Hendel）is one of the most economically damaging pests in Taiwan, and generally is controlled by insecticides. Among these control insecticides, malathion has the longest history of use. Resistance to malathion in oriental fruit flies was examined here by comparing the activity of several metabolic enzymes in resistant and susceptible colony. These two tested colonies did not show significantly difference with respect to enzyme activity of glutathione S-transferase. However, the malathion-resistant colony exhibited a higher activity than the susceptible colony did in general esterases and mixed function oxidases. Moreover, the target enzyme, acetylcholinesterase（AChE）from the resistant colony was less sensitive to the inhibition of four organophosphorus inhibitors than that of the susceptible colony by six-fold difference at least. The analytical results suggested that elevated hydrolytic and oxidative metabolic enzymes combined altered AChE with poorer catalytic efficiency might contribute to the resistance of B. dorsalis to malathion."