苦瓜素Ⅰ对亚洲玉米螟的生物活性及对其幼虫体内代谢酶活性的影响

【目的】为研究苦瓜素Ⅰ对亚洲玉米螟 Ostrinina furnacalis (Güenée)的生物活性和体内相关酶活性的影响。【方法】采用饲料混药法测定了苦瓜素Ⅰ对亚洲玉米螟生长发育和繁殖的影响，并以生命表的方法评价了苦瓜素Ⅰ对亚洲玉米螟实验种群增长的控制作用；采用酶标仪测定了苦瓜素Ⅰ对亚洲玉米螟幼虫海藻糖酶和磷酸酯酶活性的影响。【结果】用含0.25, 0.5, 1.0, 2.0和4.0 mg/g浓度苦瓜素Ⅰ的人工饲料饲喂亚洲玉米螟3龄幼虫3 d，幼虫的存活率明显降低， LC₅₀为3.2 mg/g；对幼虫体重增长的抑制作用显著，在4.0 mg/g浓度下，第1, 2和3 天体重增长的抑制率分别为76.87%, 78.24%和79.94%，且发育历期明显延长；苦瓜素Ⅰ各浓度处理组中亚洲玉米螟蛹的历期和成虫寿命与对照相比差异不显著，但苦瓜素Ⅰ明显降低了亚洲玉米螟雌成虫的产卵量，4.0 mg/g浓度下，产卵抑制率高达73.55%。苦瓜素Ⅰ对亚洲玉米螟幼虫海藻糖酶、酸性磷酸酯酶和碱性磷酸酯酶活性均有明显的抑制作用，处理24, 48和72 h后，对亚洲玉米螟幼虫海藻糖酶活性的IC₅₀分别为3.8, 2.9和4.9 mg/g；对酸性磷酸酯酶活性的IC₅₀分别为3.1, 2.6和1.5 mg/g，对碱性磷酸酯酶活性的IC₅₀分别为3.3 ,1.9和3.6 mg/g。【结论】苦瓜素Ⅰ能显著抑制亚洲玉米螟幼虫的生长发育及成虫的生殖力，使其实验种群的增长受到明显控制。苦瓜素Ⅰ抑制亚洲玉米螟幼虫体内海藻糖酶和磷酸酯酶活性是其作用机制之一。

Bioactivity of momordicin I against Ostrinia furnacalis (Lepidoptera: Pyralidae) and its effects on the metabolizing enzyme activities in larval bodies of the moth

【Aim】 This study aims to explore the effects of momordicin I on the growth and related enzyme activities of the experimental population of Ostrinina furnacalis(Güenée). 【Methods】 The effects of momordicin I on the larval weight gain, developmental duration, survival rate and fecundity of O. furnacalis were investigated by adding the compound to the artificial diet provided to O. furnacalis larvae under laboratory conditions. The life table was used to evaluate the control effects of momordicin I on the experimental population of O. furnacalis. The effects of momordicin I on activities of trehalase, alkaline phosphatase and acid phosphatase in O. furnacalis larvae were determined. 【Results】 After the 3rd instar larvae of O. furnacalis were fed with the artificial diet containing 0.25, 0.5, 1.0, 2.0 and 4.0 mg/g momordicin I for 3 d, their survival rates decreased and the LC₅₀ value was 3.2 mg/g. Momordicin I had an apparently inhibitory effect on the body weight gain of O. furnacalis larvae. After the larvae were fed with the artificial diet containing 4.0 mg/g momordicin I for 1, 2 and 3 d, their body weight gain was inhibited by 76.87%, 78.24% and 79.94%, respectively, and the developmental duration of the treated larvae was significantly longer than that of the control group. The pupal duration and adult longevity of the treated larvae were not significantly different from those of the control, while the fecundity of adults in the treatment groups was significantly lower than that of the control. The 4.0 mg/g momordicin I in the artificial diet inhibited the fecundity of adults by 73.55%. Momordicin I in the artificial diet inhibited the activities of trehalase, alkaline and acid phosphatase in O. furnacalis larvae. At 24, 48 and 72 h after the larvae were fed with the artificial diet containing momordicin I, the IC₅₀ values of the trehalase activity were 3.8, 2.9 and 4.9 mg/g, while those of the alkaline phosphatase activity were 3.1, 2.6 and 1.5 mg/g, and those of the acid phosphatase activity were 3.3, 1.9 and 3.6 mg/g, respectively. 【Conclusion】 These results suggest that momordicin I inhibits the population growth and fecundity of O. furnacalis, and its inhibition on the activities of trehalase, alkaline and acid phosphatase of larvae may be a major mechanism of action.