Crude total alkaloids were obtained from Vitex negundo L. seeds by acid solution extraction method, and its biological activity against apterous adults of Aphis gossypii Glover was determined by bioassay and biochemical analysis methods. The results show that contact toxicity of total alkaloids against apterous adults of A. gossypii is relatively high and LD^ to per apterous adult is 0. 073 |xg. After treatment of 0.500, 1.000, 2.000, 4.000 and 8.000 g · L"1 total alkaloids against apterous adults for 24, 48 and 72 h, AFCX is 1.256, 1.720 and 3.923 g · L"1, respectively, showing that total alkaloids have a certain deterrent and sustainable control effects. Compared with the control, the survival time of apterous adults treated by total alkaloids at the dose of LD^ (0. 045 |xg per apterous adult) is shorted by 7 d, and the fertility per female apterous adult is reduced by 30. 43%. And averages of honeydew excretion frequency and amount per day of per apterous adult are reduced by 4. 26 drops and 27. 10 |xg, respectively, and the difference with the control reaches the significant level. Under in vitro condition, inhibition of total alkaloids on activities of carboxylesterase ( CarE), acetylcholinesterase ( AchE) and glutathione-S-transferase (GST) from apterous adults is significant and ICX is 0.778, 1.901 and 4.216g · L"1, respectively, but total alkaloids have an obvious activation on polyphenol oxidase ( PPO) with an obvious dose-effect relationship. After treatment of total alkaloids for 3, 6, 12 and 24 h at the dose of LDw (0.073 |i,g per apterous adult) , activities of CarE, AchE and GST of apterous adults in vivo are significantly lower but PPO activity is significantly higher than those of the control. It is suggested that the insecticidal action mechanism of total alkaloids from V. negundo seeds against apterous adults of A. gossypii relates to its effect on some enzyme activities.%采用酸水溶液提取法获得黄荆(Vitex negundo L.)种子总生物碱粗品,通过生物测定和生化分析方法研究了黄荆种子总生物碱对棉蚜(Aphis gossypii Glover)无翅成蚜的生物活性.结果显示:黄荆种子总生物碱对棉蚜无翅成蚜的触杀毒力较高,对单头棉蚜无翅成蚜的LD50为0.073 μg；用质量浓度0.500、1.000、2.000、4.000和8.000g·L-1总生物碱处理棉蚜无翅成蚜后24、48和72 h的忌避中浓度(AFC50)分别为1.256、1.720和3.923 g·L-1,具有一定的忌避和持续控制作用；用总生物碱LD30剂量(每头0.045 μg)处理棉蚜无翅成蚜,其存活时间较对照缩短7d,单头雌成蚜的繁殖力较对照降低了30.43％；单头棉蚜无翅成蚜每天的平均排蜜频率和排蜜量分别较对照减少了4.26滴和27.10 μg,差异达显著水平.在离体条件下,黄荆种子总生物碱对棉蚜无翅成蚜的羧酸酯酶、乙酰胆碱酯酶和谷胱甘肽-S-转移酶的活力有显著的抑制作用,IC50分别为0.778、1.901和4.216 g·L-1；但对多酚氧化酶的活力则有明显的激活作用,激活程度呈明显的量效关系.用总生物碱LD50剂量(每头0.073 μg)处理棉蚜无翅成蚜后3、6、12和24h,成蚜体内羧酸酯酶、乙酰胆碱酯酶和谷胱甘肽-S-转移酶的活力显著低于对照,而体内的多酚氧化酶活力则显著高于对照.研究结果表明:黄荆种子总生物碱对棉蚜无翅成蚜的杀虫作用机制与其对几种酶活力的影响效应相关.
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