Molluscicidal activities of green-synthesized Alstonia congensis silver nanoparticles

Objective:To evaluate the efficacy of Alstonia congensis green-synthesized nanoparticles as a molluscicide against snail hosts of trematodes.Methods:The ethanolic leaf extract of Alstonia congensis was used to synthesize silver nanoparticles.The formulation was characterized by Fourier transform infrared spectroscopy,X-ray powder diffraction,and scanning electron microscope/energy-dispersed X-ray.The ovicidal and molluscicidal activities of the Alstonia congensis extract and its nanoparticles were tested against Physa acuta and Bulinus forskalii at different concentrations.Results:The green-synthesized nanoparticles inhibited embryonic development within the egg masses of the two snails in all the tested concentrations.Alstonia congensis extract did not show molluscicidal properties against adult Physa acuta but showed a very weak activity against Bulinus forskalii.Moreover,the synthesized nanoparticles showed significantly high molluscicidal activity against adult snails within 5-40 min of exposure in a concentration-dependent manner(P<0.05).Conclusions:The Alstonia congensis-based nanoparticles show molluscicidal activities against adults and embryos of Physa acuta and Bulinus forskalii,and can be further explored as a potent molluscicide for the control of intermediate host of trematode parasites.

Molluscicidal effect of green synthesized silver nanoparticles using Azadirachta indica on Biomphalaria alexandrina snails and Schistosoma mansoni cercariae

Objective:To assess the molluscicidal effect of the eco-friendly green synthesized neem silver nanoparticles(neem-Ag NPs)against Biomphalaria alexandrina,the snail intermediate host for Schistosoma mansoni,and their cercaricidal potential.Methods:Methanol extracts from neem fruits were used for green synthesis of neem-Ag NPs.The neem-Ag NPs were characterized using UV-visible absorption spectra,dynamic laser light scattering technique,and transmission electron microscopy.The potential molluscicidal effect against adult and juvenile Biomphalaria alexandrina and the effect of the sub-lethal concentration on hatching of snail eggs and Schistosoma mansoni cercariae were evaluated.Results:The surface plasmon resonance of neem-Ag NPs showed a sharp absorption peak atλ_(max)=518 nm together with multiple peaks.The hydrodynamic diameter was(77.15±34.53)nm,the polydispersity index(0.338±0.000)and the zeta-potential-14.07 mV.Moreover,transmission electron microscopy showed that the average size of the nanoparticles was(27±2)nm.Agglomeration was evident and a light-colored capping layer could be seen coating the nanoparticles.Juvenile snails(LC_(50):0.83 ppm)were more susceptible to neem-Ag NPs than adults(LC_(50):1.07 ppm).In addition,neem-Ag NPs and neem at LC_(50)concentrations inhibited the egg-hatching of snails and showed cercaricidal activity in a time-dependent manner.Conclusions:Neem-Ag NPs have lethal activities against Biomphalaria alexandrina snails and their eggs,as well as Schistosoma mansoni cercariae.Hence,neem-Ag NPs could be a potential agent to control schistosomiasis.

紫茎泽兰对钉螺代谢活性影响

为探究紫茎泽兰对钉螺活性的影响,采用超高效液相色谱-四极杆飞行时间质谱联用技术(UPLC-Q-TOF/MS),分别检测紫茎泽兰处理钉螺组、氯硝柳胺处理钉螺对照组和空白对照组的钉螺情况,用主成分分析(PCA)、偏最小二乘法判别分析(PLS-DA)及正交偏最小二乘法判别分析(OPLS-DA)进行联合统计分析,筛选差异代谢物。结果表明紫茎泽兰活性成分可以干预钉螺的生长代谢,共筛选出79种差异显著代谢物,甘氨酸等31个代谢物显著上调,L-苏氨酸等48个代谢物显著下调,并得到18条代谢通路阐明了紫茎泽兰干预钉螺活性的代谢机制,为将紫茎泽兰研发为灭螺剂及灭螺药物靶标筛选奠定了理论基础。

Laboratory assessment of the molluscicidal and cercariacidal activities of Balanites aegyptiaca

Objective:To assess the molluscicidal and cercariacidal activities of aqueous extracts of Balanites aegyptiaca(B.aegyptiaca)against EthiopianBiomphalaria pfeifferi(B.pfeifferi),Lymnaea natalensis(L.natalensis)and Schistosoma mansoni(S.mansoni)cercariae.Methods:Extracts of seeds,endocarp,mesocarp,and fruit of B.aegyptiacawere tested for their activities against adultB.pfeifferiandL.natalensis.The cercariacidal activity of the seeds of the plant was also evaluated againstS.mansoni.Bioassays were carried out following the methods recommended by WHO.Snail mortalities were compared between each plant part and snail species,and LC50and LC90values for the plant parts tested were computed.The cercariacidal activity of the plant was assessed by exposing the mice to the cercariae pre-exposed to aqueous extract of B.aegyptiacaseeds.Results:For the molluscicidal activities of seeds,endocarp,mesocarp and whole fruit,the LC50values againstB.pfeifferiwere 56.32,77.53,65.51 and 66.63 mg/L,respectively,while the respective LC90values were 77.70,120.04,89.50 and 97.55 mg/L.Similarly,the LC50values for the seeds,endocarp,mesocarp and whole fruit againstL.natalensiswere 80.33,92.61,83.52 and 87.84mg/L,respectively,while the respective LC90values were 102.30,138.21,115.42 and 127.69 mg/L.B.pfeifferiwere found to be more susceptible toB.aegyptiacathanL.natalensis.S.mansoni cercariae exposed to 15 mg/L of extract of seeds were incapable of infecting mice.The mean egg load of tissue was reduced in mice infected with the cercariae exposed to 5 and 10 mg/L of the extract.Conclusions:The aqueous extracts of different parts ofB.aegyptiacaexhibited reasonable molluscicidal activity againstB.pfeifferiandL.natalensis,as well as cercariacidal activity againstS.mansonicercariae.However,comprehensive laboratory evaluation is recommended prior to field tests of the plant parts since their impact on other aquatic biota is not known.

Synthesis of New Fluorine/Phosphorus Substituted 6-(2’-Amino Phenyl)-3-Thioxo-1,2,4-Triazin-5(2H, 4H)One and Their Related Alkylated Systems as Molluscicidal Agent as against the Snails Responsible for Bilharziasis Diseases

New fluorine substituted 6-(5’-fluoro-2’-triphenylphosphiniminophenyl) 3-thioxo-1,2,4-triazin-5 (2H, 4H) one (2) was obtained via Wittig’s reaction of the corresponding 6-(5’-fluoro-2’-amino-phenyl)-3-thioxo-1,2,4-triazinone (1). Behavior of compound 2 towards alkylating agents and/or oxidizing agents was studied were, N-hydroxyl (3), Mannich base (4,5), S-alkyl (6,7,8) and thiazolo [3,2-b][1,2,4] triazinones (10-14) and or 3-disulfide (18), 3-sulfonic acid 19 and 1,2,4-triazin-3,5-Dionne (20) derivatives obtained. Structures of the new products are established by elemental and spectral data. The new targets obtained screened as Molluscicidalagents against Biomophlaria Alexandrina snails responsible for Bilharziasis diseases, in compare with Baylucide as standard drug.

Synthesis of Some More New Fluorinated 1,2,4-triazino[3,4-b][1,3,4]Thiadiazolonesand Their Molluscicidal Against Selective Snails - Part I

Some more new fluorinated 1,2,4-triasino[3,4-b][1,3,4]thiadiazolones （6-9 and 11-16） have been synthesized from cyclocondensation of 5-hydrazino-2-（4＇-fluorophenyl）-1,3,4-thiadiazole with bifunctional oxygen and halogen compounds. Structures of the products have been deduced from their elemental, chemical and spectral data （UV, IIL 1H/13C NMR （nuclear magnetic resonance） and mass）. All the new compounds evaluated as molluscicidal against towards snails which responsible for Bilharziasis diseases.

《血吸虫病防治领域杀螺剂的室内和现场药效试验指南》摘译

世界卫生组织(WHO)于2019年发布了《血吸虫病防治领域杀螺剂的室内和现场药效试验指南》(以下简称《指南》)。该《指南》旨在为杀螺剂的药效试验和评估提供标准化流程,从而为所在国监管部门进行产品登记等工作提供依据。本文对该《指南》的背景以及室内试验、小规模现场试验、大规模现场试验等主要内容进行翻译,供读者参考。

银杏内生真菌CS15菌株鉴定与杀螺作用的初步研究

目的:研究可能影响银杏内生真菌CS15菌株杀螺效果的相关因素。方法:应用形态学特征观察结合rDNA-ITS序列综合分析对该菌株进行鉴定。使用浸泡法配制不同浓度的菌株CS15发酵液;实验随机分为4组(超纯水对照组和1%、2%、4%滤液组),评定不同浓度CS15发酵滤液对钉螺的杀灭效果。采用蒽酮比色定量分析法检测发酵滤液浸泡处理后的螺体内糖原含量变化。结果:菌株经分离培养、形态学及分子生物学鉴定,该菌株为草酸青霉真菌。实验组菌株CS151%、2%、4%浓度下的发酵滤液均有一定的杀螺效果。其中在24 h后,以4%发酵滤液杀螺效果最佳(P<0.05),在48 h和72 h后,4%发酵滤液杀螺效率优于1%和2%发酵滤液(P<0.05)。经不同浓度CS15发酵滤液处理后,钉螺软体组织内糖原含量均明显降低,以4%发酵滤液组最为明显(P<0.05)。结论:在本实验条件下,银杏内生真菌CS15发酵滤液对湖北钉螺具有毒杀效应,以4%发酵滤液杀螺效果最佳,其杀螺因素可能与螺软体组织内糖原合成相关。

4种常见杀螺剂对稻田福寿螺的防效试验

筛选稻田福寿螺防控药剂,指导田间合理用药。采用田间小区试验的方法,比较了4种常见杀螺剂对稻田福寿螺的防控效果。结果表明,整体防效为70%杀螺胺可湿性粉剂>70%杀螺胺乙醇胺盐可湿性粉剂>6%聚醛·甲萘威颗粒剂>6%四聚乙醛颗粒剂;其中70%杀螺胺可湿性粉剂420 g a.i./hm^(2)处理的防效最好,药后2、7 d防效分别为82.34%、88.32%,其持效期长,药后14 d防效为92.59%,抑卵效果为93.89%,保苗率达99.09%;6%四聚乙醛颗粒剂在药后2、7、14 d防效分别为65.31%、78.82%、85.57%,也表现出较好的杀螺效果。70%杀螺胺可湿性粉剂、70%杀螺胺乙醇胺盐可湿性粉剂、6%聚醛·甲萘威颗粒剂和6%四聚乙醛颗粒剂4种常见杀螺剂均可用于稻田福寿螺的防治,宜交替使用。

氯硝柳胺悬浮剂的研制及其杀螺效果评价

目的 研制氯硝柳胺悬浮剂 ,测定其性能及杀螺效果。方法 将氯硝柳胺原药与润湿剂、分散助悬剂和粘度调节剂等助剂按一定工艺混合 ,经砂磨机研磨 ,制成悬浮剂 ;进行分散性、悬浮性、稳定性等性能评价 ,确定最佳配方组成及产品的技术质量指标 ,并对产品进行实验室和现场杀螺效果评价。结果 最佳配方 (W/W)为 :2 5 %氯硝柳胺、1.5 % - 2 .0 %润湿剂 (RS3)、4 %分散助悬剂(FS2 )和 0 .10 %增稠剂 ,少量其它助剂和水 ;技术质量指标 :含量氯硝柳胺≥ 2 5 % (W/W) ,悬浮率≥90 % ,p H4 - 7,细度 (≤ 4 4 μm的粒子 )≥ 98% ,粘度≤ 6 0 0 mpa.s,冷、热贮稳定性符合国家农药标准。室内浸杀钉螺 2 4、4 8、72 h,氯硝柳胺悬浮剂的 L C50 分别为 0 .0 4 74、0 .0 4 12、0 .0 4 12 m g/L;氯硝柳胺乙醇胺盐可湿性粉剂的 L C50 分别为 0 .0 94 7、0 .0 5 83、0 .0 4 4 2 m g/L。 2 .0 g/(L· m2 ) 2 5 %氯硝柳胺悬浮剂 [含氯硝柳胺 0 .5 g/(L· m2 ) ]现场进行喷洒灭螺 ,3、7、15 d后 ,钉螺死亡率分别为95 .77%、99.0 7%、97.0 9% ;2 .0 g/(L· m2 ) 5 0 %氯硝柳胺乙醇胺盐可湿性粉剂 [含氯硝柳胺 1.0g/(L · m2 ) ]的钉螺死亡率分别为 97.37%、95 .19%、97.4 1%。结论 新研制的悬浮剂 ,质量稳定 ,分散性好 ,方便?

新型灭螺剂氯代水杨胺灭螺效果研究

目的观察新型灭螺剂氯代水杨胺(LDS)的灭螺效果。方法采用浸杀法、喷洒法和撒粉法,将10%LDS和50%氯硝柳胺乙醇胺盐(WPN)在实验室分别配成0.05、0.1、0.2、0.4、0.8、1.6、3.2mg/L(g/m2)7个浓度,在现场分别配成0.2、0.4、0.8mg/L(g/m2)3个浓度,平行比较两种药物实验室24、48、72h和现场1、3、7d的灭螺效果。两种药物均以0.4mg/L(g/m2)浓度评价其灭螺效果。结果在实验室温度23～25℃条件下,LDS和WPN的钉螺死亡率,浸杀72h分别为100.0%和96.7%;喷洒7d分别为100.0%和96.0%;撒粉7d分别为92.0%和94.0%。在现场温度15～24℃条件下,LDS和WPN的钉螺死亡率,浸杀72h分别为100.0%和96.0%;喷洒7d分别为100.0%和96.9%;撒粉7d分别为100.0%和94.1%。结论新型灭螺剂氯代水杨胺的灭螺效果与氯硝柳胺乙醇胺盐基本相同,但灭螺费用降低。

40种植物甲醇提取物的杀螺活性研究

对40种药用或有毒植物甲醇提取物的室内杀螺活性测定结果表明:木荷、黄姜、博落回等3种植物提取物在浓度为100mg/L时,浸杀福寿螺幼螺48h,死亡率为100%;50mg/L时,浸杀72h,死亡率为98.28%以上。其中木荷、博落回对福寿螺有良好的抑制上爬作用,具有进一步研究价值。

16种植物提取物对福寿螺杀螺效果的研究

通过室内生物测定的方法就16种常见杀虫杀螺植物醇提物对福寿螺的杀螺效果进行检测,结果表明,在0.25-4mg/mL浓度范围内,博落回醇提物溶液对福寿螺的杀螺效果最好,其后依次为夹竹桃、魔芋、乌药和美洲商陆。5种植物醇提物溶液对福寿螺幼螺具有相对较强的毒杀作用,对福寿螺成螺也具有一定的毒杀作用。在最高浓度4 mg/mL时,5种植物醇提物溶液对幼螺的相对毒杀率分别为83.15%、55.06%、46.07%、37.08%和34.83%,对成螺的相对毒杀率分别为35.56%、28.89%、26.67%、23.33%和17.78%。可见,博落回等5种植物具有开发为福寿螺植物源杀螺剂的潜力。

肟基磷酸酯类化合物及与氯硝柳胺复方增效的杀螺研究

本文报道了24种肟基磷酸酯化合物的杀螺结果，发现化合物2、10、11和14等均具有杀螺作用，在25℃室温时，浸杀48h，1mg／L的杀螺率分别为100．0％、93．3％、83．3％和96．7％；LD50分别为0．6017、0．3969、0．7973和0．3260mg／L。将上述化合物与氯硝柳胺组成（1∶1）复方，化合物5和6与氯硝柳胺组成的复方均具有较好的增效杀螺作用，增效比（SR）值分别为2．32和3．50。

氯硝柳胺对鱼类和溞类的毒性研究

作者采用国际标准法,测定了灭螺药氯硝柳胺对水环境的代表性实验生物斑马鱼(Brachydanio rerio)及大型水溞(Daphnia magna)的毒性。结果表明氯硝柳胺对斑马鱼的LC_(50)值,24h为0.80mg/L,48h为0.74mg/L,96h为0.52mg/L。对大型溞的LC_(50)值,24h及48h分别为0.54mg几及0.42mg/L。对大型溞的EC_(50)值24h及48h分别为0.54mg/L及0.38mg/L。表明氯硝柳胺对鱼类及溞类的毒性都很大,为极毒物质。因此,在应用氯硝柳胺灭螺时,应严加注意,防止污染水环境而毒害鱼类。

密达(META)沙粒剂杀灭钉螺效果的研究

目的对密达沙粒剂杀灭钉螺效果进行实验研究和评价。方法采用撒施法对密达10％沙粒剂杀灭钉螺效果进行实验室和江滩现场实验。结果室内撤施密达沙粒剂1．6g／m2以上7d钉螺死亡率均超过93％，钉螺死亡率随施药时间的延长而呈上升趋势，目测概率法计算3dLD50＝1．12～2．25g／m2；江滩现场实验显示3．2g／m2以上杀螺效果较明显，同时还显示在一定剂量范围内，增大用药量似可继续提高效果。结论密达沙粒剂具有明显的杀灭钉螺作用，且对非靶生物毒性较低，具有良好的实用价值，值得进一步研究。

密达利杀灭湖北钉螺效果的研究

目的实验室和现场试验评价密达利(META-Li,40%四聚乙醛水乳剂)杀灭湖北钉螺的效果。方法室内:采用泥缸喷洒法、烧杯浸杀法和三角沉淀杯上爬法,用敲击法观察不同时间、不同浓度密达利对湖北钉螺的杀灭和抑制上爬作用。现场:选择安徽省芜湖县草滩进行现场喷洒试验,密达利剂量为1、2和4g/m2,设氯硝柳胺药物对照剂量为1g/m2和清水空白对照组,观察施药后3、7和15d检查钉螺存活情况。结果室内喷洒试验:24、48和72h的半数致死剂量(LD50)分别为0.78、0.44和0.46g/m2;室内浸杀试验:24、48、72h的半数致死浓度(LC50)分别为44.4、27.4和24.8mg/L;24h抑制钉螺上爬半数有效浓度(EC50)为5.86mg/L。现场喷洒试验:密达利2g/m2喷洒后7d钉螺死亡率大于90%,灭螺效果和氯硝柳胺1g/m2相当(P>0.05)。结论密达利室内及现场喷洒灭螺效果明显,有抑制钉螺上爬作用。

血水草生物碱杀灭钉螺的研究

目的 探讨血水草生物碱在实验室不同温度下杀灭钉螺的效果。方法 在实验室配制不同浓度的血水草生物碱溶液 ,观察在 2 0、2 5、30℃时浸泡 2 4、4 8、72、96 h的钉螺死亡率 ;观察杀螺卵效果 ;观察钉螺上爬率。结果 浸泡 72 h钉螺死亡率为 10 0 %的血水草生物碱溶液的浓度及温度分别为 :1.2 5 mg/ L、30℃ ;2 .5、5、10 m g/ L 均为 2 5℃。 5 mg/ L 时能明显抑制钉螺上爬。螺卵在 5 m g/ L溶液浸泡 72 h孵出率为 0～ 10 %。结论 血水草生物碱有较好杀灭钉螺的效果 ,是一种有研究价值的植物灭螺剂。

10种植物提取物对稻田福寿螺的毒杀活性

浸提法获得四川10种常见有毒植物的水提物和乙醇提取物并追踪对福寿螺的毒杀活性。结果表明,马桑(Coriaria sini-ca)、紫堇(Corydalis edulis)、紫茎泽兰(Eupatorium adenphorum)、夹竹桃(Nerium indicum)等4种植物对福寿螺有较强毒杀活性,其中马桑叶的毒杀活性最强,采用其水提物和质量浓度为1 mg/mL的乙醇提取物浸杀福寿螺,48 h死亡率100%,夹竹桃、紫堇和紫茎泽兰杀螺作用仅次于马桑。

夹竹桃灭钉螺活性成分的分离纯化

夹竹桃叶提取液对钉螺具有明显的毒杀作用．采用溶剂提取和高效液相色谱的方法，分离了新鲜夹竹桃叶中的成分经过灭钉螺实验，得到一种有灭钉螺作用的成分，其浓度为5mg·L-1时24h灭钉螺效果为63％夹竹桃及其提取物在钉螺的防治中显示着潜在的应用前景．