蓖麻叶片粗提物对黄瓜瓜绢螟的作用

为了测定蓖麻对瓜绢螟的作用,也为黄瓜害虫无公害控制提供新的手段,用不同浓度的蓖麻叶片粗提物处理黄瓜叶片,测定瓜绢螟取食量、存活率及体内解毒酶活性的变化。结果显示,蓖麻叶片粗提物对瓜绢螟的取食和存活有明显的抑制作用,处理浓度越大,取食量和存活率越小。如用稀释200倍的蓖麻叶片粗提液处理黄瓜叶片,瓜绢螟的取食面积(1.89 cm2)仅为对照(3.51 cm2)的53.7%,存活率为对照的2.3%;600倍浸提液处理的瓜绢螟取食面积(3.43 cm2)为对照的97.7%,存活率为对照的51.4%。瓜绢螟幼虫虫龄对粗提物的作用有明显影响,粗提物对低龄幼虫的作用明显强于高龄幼虫,200倍液处理24 h后,1龄幼虫的存活率(22.22%)仅为5龄幼虫(66.67%)的33.33%。不同剂量蓖麻叶片粗提物处理后,瓜绢螟体内的谷胱甘肽转移酶、羧酸脂酶、多功能氧化酶等解毒酶活性迅速上升,随着处理剂量的增加,解毒酶的活性上升幅度增大。取食用稀释200倍的蓖麻粗提液处理的黄瓜叶片24 h后,1龄幼虫和5龄幼虫体内谷胱甘肽转移酶活性分别较对照高23.79%和78.02%,羧酸脂酶活性分别较对照高72.42%和23.84%,多功能氧化酶活性分别较对照高100.58%和122.39%。结果表明,蓖麻叶片粗提物对瓜绢螟有明显的拒食和毒杀作用。

Effect of castor leaf alcohol extract on Diaphania indica

Castor plant is increasingly cultivated for use as bio-energy. Castor leaves are also used as bio-pesticides. This study explored the effects of alcohol extracts from castor leaves on Diaphania indica Saunders in cucumber plants. Crude castor leaf extracts were diluted at different degrees to investigate their effects on D. indica feeding on leaves of cucumber plants under greenhouse conditions. The changes in feeding amounts, survival rates and detoxification enzyme activities of D. indica were measured. The results showed that crude castor leaf extracts significantly inhibited the food consumption and the survival rates of D. indica larvae. The higher the concentrations of the extracts, the less were the consumption and survival rates. When extract was diluted at 200 times, average consumed area of cucumber leaf was 1.89 cm², which was only 53.7% of the control treatment and 97.7% of treatment with extract diluted at 600 times. At dilution rate of 600 times, survival rate of D. indica larvae was 45.65%, much lower than that of the control (88.89%). Different D. indica larvae instars responded differently to castor leaf extracts. Higher effects were observed at lower larvae ages. When treated with extracts diluted 200 times for 24 h, survival rates of first and fifth instars were 22.22% and 66.67%, respectively. Compared with the fifth instar, survival rate of the first instar was only one-third. Gluthione transferase, carboxylesterase and functional oxidase activities in D. indica larvae increased rapidly after D. indica larvae fed on cucumber leaves treated with crude castor leaf extracts. Under treatment with 200 times dilution of crude castor leaf extracts for 24 h, the first and fifth instars of D. indica larvae were 23.79% and 78.02% higher in gluthione transferase activity, 72.42% and 23.84% higher incarboxylesterase activity and 100.58% and 122.39% higher in functional oxidase activity, over those under the control. With increased dose of crude extracts, an obvious increase in detoxification enzyme activity was noted. The results indicated that crude castor leaf extracts were sufficient anti-feedants and poisons to D. indica.