黄杜鹃叶提取物对桔二叉蚜的毒力及其毒理研究

黄杜鹃(Rhododendron molle)叶提取物对桔二叉蚜(Toxoptera aurantii)有较强的毒杀作用．黄杜鹃叶的乙醇总提物对桔二叉蚜无翅成蚜的半致死浓度(LC50)为1558mg/L在黄杜鹃叶提取物的4种萃取物中，乙酸乙酯萃取物对桔二叉蚜的毒力最强，其LC50为364mg／L，表明黄杜鹃叶含有的杀虫活性物质主要存在于乙酸乙酯萃取物中．实验表明，黄杜鹃叶乙酸乙酯萃取物对桔二叉蚜的乙酰胆碱酯酶(AchE)和羧酸酯酶(CarE)有一定的抑制作用．桔二叉蚜经10000mg/L的黄杜鹃叶乙酸乙酯萃取物溶液处理24h后，其体内的乙酰胆碱酯酶的活性为对照组的0．6543倍，羧酸酯酶的活性仅为对照组的0．4021倍．图2表4参10

TOXICITIES OF THE EXTRACTS FROM RHODODENDRON MOLLE AGAINST TOXOPTERA AURANTII AND THEIR APHID-KILLING MECHANISM

Toxicities of several extracts from the leaves of Rhododendron molle against citrus aphids (Toxoptera aurantii ) were studied. The results showed that the total ethanol extract from the leaves of R. molle was highly effective in killing T. aurantii. Its median lethal concentration against apterous aphid was 1 558 mg/L at 48 h after treatment. Of the 4 extracts from the total ethanol extract, ethyl acetate extract, whose LC 50 was 364 mg/L, was the most effective against T. aurantii. Analyzing and measuring enzymatic activity by PAGE, it was indicated that ethyl acetate extract was able to inhibit effectively the activities of acetylcholinesterase(AchE) and carboxylesterase(CarE) of T. aurantii. 24 h after treatment by ethyl acetate extract, whose concentration was 10 000 mg/L, the activity of AchE was 65.43% of that of the comparison, and the CarE just 40.21%. This could be one of the deaths of citrus aphids. Fig 2,Tab 4,Ref 10