樟树水浸液对钉螺的生态毒理学效应

用樟树(Cinnamomum camphora)新鲜根皮、茎皮、叶为材料,设置1%、0.5%、0.1%、0.05%4个不同浓度梯度的水浸液处理钉螺,以清水和1 mg/L浓度的氯硝柳胺溶液为对照,统计钉螺死亡率,并分析钉螺过氧化氢酶(CAT)和过氧化物酶(POD)活性及采用透射电镜分析亚显微结构损伤情况。结果表明:(1)樟树各部分的水浸液均有很好的灭螺效果。钉螺死亡率随处理浓度的增加和时间的延长呈上升趋势,0.5%—1.0%以上的樟树根皮、茎皮、叶水浸液均可达到100%的毒杀钉螺致死效果,与1 mg/L氯硝柳胺溶液的灭螺效果相当;灭螺效果顺序依次为:根皮茎皮叶。(2)在处理初期,钉螺体内过氧化氢酶和过氧化物酶活性明显增强,但随处理时间延长,其活性急剧降低;过氧化物酶同工酶谱显示,处理24—48 h后钉螺酶活高于对照组,处理72—96 h后酶活最强,而处理120 h酶活则大大减弱。(3)钉螺肝细胞亚显微结构观察表明,随处理时间的延长,线粒体、内质网、细胞核等结构损伤越来越严重。这些结果表明樟树水浸液对钉螺肝脏造成过氧化伤害和细胞器结构损伤,具有很好的杀螺效果,可作为生态工程抑螺林树种。

Ecotoxicological effects of water extract of Cinnamomum camphora on oncomelania hupensis

Control of infection by Schistosomiasis, which causes a severe health problem in human, has been a challenging task for most endemic countries in the tropics and subtropics. Schistosomiasis remains a public health concern in China after a concerted effort in the past decades. Oncomelannia hupensis, the only intermediate host of Schistosome, is regarded as the weakest link in the life cycle of Schistosome. Killing O. hupensis can control the epidemic of Schistosomiasis in public water sources. Plant molluscicide is considered as the best reagent as judged by public safety, financial cost, and environmental protection. We used Cinnamomum camphora here in this experiment. Extract of leaf, barks of root and shoot of C. camphora were used at 4 concentrations(1%, 0.5%, 0.1% and 0.05%) (water and 1mg/L Niclosamidum as the control)in the experiment against snails O. hupensis. The mortality of snails was investigated. The activities of catalase (CAT), peroxidase (POD) and TEM ultralstructure of O. hupensis liver cell were analyzed in the experiment. The results showed that the molluscicidal effect of the lixivium of C. camphroa against O. hupensis is excellent. The mortality of the snails correlated with the concentrations of the lixivium and the time of treatment. The mortality of the snails treated with water extracts from leaf, barks of root and shoot of C. camphora in 4 concentrations in 120 h was up to 100%, which is similar with that of 1mg/L Niclosamidum. The molluscicidal activity order of different parts from C. camphroa against O. hupensis ranks: root bark > stem bark > leave. Treatment with 0.5% leaf water extract induced a significant increase of the activities of CAT and POD in the early period time points (48 h and 73 h respectively) followed by a dramatic decrease. Further more, 0.5% water extract of leaf causes a marked damage in liver as judged by the TEM ultrastructure analysis. For example, 48 h treatment with 0.5% leaf water extract caused a slight damage to nuclei of hepatocytes of the snail, which manifested as slightly nuclei swelling; loosed chromatin; reduced number of mitochondria and even condensed or ruptured mitochondria; expanded or fragmented reticulum cavity of rough endoplasmic in cytoplasm. The damage to hepatocytes was further exaggerated 72 h after treatment: broken nuclei of hepatocytes; reduced chromatin mass; organelles cavitation; vague and broken mitochondria Cristae. These hepatocytes were filled with dense bodies and different types of gas vacuoles. The cell membrane was raptured. We conclude that the plant C. camphroa demonstrates a strong molluscicidal activity in a peroxide-dependent manner, which damages the organelles of hepatocytes. Thus, C. camphroa will be better plant resource in controlling the snails in ecological projects.