氯代水杨胺缓释颗粒剂杀灭钉螺效果评价

The Molluscicidal Effect of Chlorosalicylicamide Sustained-release Granules on Oncomelania hupensis

目的评价氯代水杨胺缓释颗粒剂(LDS-SRG)杀灭湖北钉螺(Oncomelania hupensis)的效果。方法将5%、10%LDS-SRG分别配置成有效浓度/剂量为0.1、0.2、0.4、0.8、1.6、3.2、6.4 mg/L(浸杀法)或g/m^2(喷撒法)的溶液或药剂。实验室浸杀试验中,各浓度分别投螺袋3包,每包30只钉螺,分别于24、48、72 h各取1包螺袋,计数试验螺数和死亡螺数,计算钉螺死亡率。实验室喷撒试验中,每剂量投放钉螺约200只,于施药后3、7 d各取约50只钉螺,施药后14 d取其余全部钉螺,分别计算钉螺死亡率。现场浸杀试验中,LDS-SRG浓度为0.4、0.8、1.6 g/m^3,每浓度投螺袋6包,每包30只钉螺,分别于24、48、72 h各取2包螺袋,计算钉螺死亡率。现场喷撒试验中,LDS-SRG剂量为0.8、1.6、3.2 g/m^2,每剂量施药于3个有螺沟渠小区(每小区约100 m^2),于施药后3、7和14 d,每小区抽取10框钉螺,计算钉螺死亡率。全部试验均设50%氯硝柳胺乙醇胺盐可湿性粉剂(WPN)1.0 mg/L或g/m^2或g/m^3药物对照组和空白对照组。结果实验室浸杀试验结果显示,5%LDS-SRG 0.1~6.4 mg/L浸杀72 h,以及1.6~6.4 mg/L浸杀48 h,钉螺死亡率均为100%,24、48、72 h半数致死浓度(LC_50)分别为0.70、0.01、0.01 mg/L;10%LDS-SRG 0.1~6.4 mg/L浸杀72 h,以及0.2~6.4 mg/L浸杀48 h,钉螺死亡率均为100%,24、48、72 h LC_50分别为0.15、0.01、0.01 mg/L。实验室喷撒试验结果显示,5%LDS-SRG 1.6、6.4 g/m^2施药后7 d,以及3.2、6.4 g/m^2施药后14 d,钉螺死亡率均>95%,其3、7、14 d半数致死剂量(LD_50)分别为0.06、0.16、0.18 g/m^2;10%LDS-SRG 1.6 g/m^2施药后14 d,以及6.4 g/m^2施药后7 d,钉螺死亡率均>95%,其3、7、14 d LD_50分别为3.29、0.75、0.16 g/m^2;5%LDS-SRG各剂量处理不同时间的钉螺死亡率均高于药物对照组(P<0.05)。现场浸杀试验结果显示,5%、10%LDS-SRG 1.6 g/m^3浸杀72 h,钉螺死亡率分别为96.43%和98.21%,与药物对照组的100%相比,差异均无统计学意义(P>0.05)。现场喷撒试验结果显示,5%、10%LDS-SRG 3.2 g/m^2施药后3、7、14 d,钉螺死亡率分别为93.99%、91.18%、86.48%和94.95%、93.50%、85.43%,均高于相应药物对照组的82.83%、72.38%、48.38%(P<0.05);5%LDS-SRG 0.8 g/m^2现场喷撒14 d和1.6 g/m^2现场喷撒3 d,钉螺死亡率为66.51%和84.61%,均高于10%LDS-SRG的20.13%和43.06%(P<0.05)。结论5%、10%LDS-SRG分别采用浸杀法和喷撒法灭螺,均达到农药登记用杀钉螺剂药效评价指标要求。

Objective To evaluate the molluscicidal effect of the chlorosalicylicamide sustained-release granules（LDS-SRG） on Oncomelania hupensis. Methods Seven effective concentrations or dosages of LDS-SRG, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 and 6.4 mg/L （for immersion test） or g/m^2（for spraying test）, were prepared from the original 5% and 10% concentrations or dosages in the laboratory. In the immersion test, each concentration of LDS-SRG was incubated with 3 packs of snails（30 snails in each pack）, and each pack was taken for snail counting at 24, 48 and 72 h respectively. In the spraying test, each dosage of LDS-SRG was applied to 200 snails, and the snail mortality was calculated in 50 randmoly collected snails on days 3 and 7, and in the whole on day 14 after administration. In the field immersion test, LDS-SRG at concentrations of 0.4, 0.8 and 1.6 g/m^3 was incubated with 6 packs of snails （30 snails in each pack）, and each 2 packs were taken at 24, 48, and 72 h to calculate the snail mortality. In the field spraying test, 0.8, 1.6 and 3.2 g/m^2 LDS-SRG was sprayed in 3 snail-positive ditches （～100 m^2）, and 10 boxes of snails were selected in each ditch on days 3, 7 and 14 to calculate the snail mortality. The 50% wettable powder of niclosamide ethanolamine salt （WPN） with effective concentrations or dosages of 1.0 mg/L （or g/m^2 and g/m^3） was used as the positive control. Fresh water served as the blank control. Results In the labratory immersion test using the original concentration of 5%, both 0.1-6.4 mg/L LDS-SRG for 72 h and 1.6-6.4 mg/L LDS-SRG for 48 h caused 100% mortality; and the concentration lethal to 50% （LC50） at 24, 48 and 72 h was 0.70, 0.01 and 0.01 mg/L respectively. When using the original concentration of 10%, both 0.1-6.4 mg/L LDS-SRG for 72 h and 0.2-6.4 mg/L LDS-SRG for 48 h caused 100% mortality; and the LC50 at 24, 48 and 72 h was 0.15, 0.01 and 0.01 mg/L respectively. The labratory spraying test showed that 7-day administration of 1.6 and 6.4 g/m^2 LDS-SRG as well as 14-day administration of 3.2 and 6.4 g/m^2 LDS-SRG prepared from 5% dosage, resulted in a snail mortality〉95%, with the LD50 on days 3, 7 and 14 being 0.06, 0.16, and 0.18 g/m^2; 14-day administration of 1.6 g/m2 LDS-SRG as well as 7-day administration of 6.4 g/m^2 LDS-SRG prepared from 10% dosage, resulted in a snail mortality〉95%, with the LD50 on days 3, 7 and 14 being 3.29, 0.75, and 0.16 g/m^2. The mortality by various dosages of LDS-SRG prepared from 5% dosage was significantly higher than that of the control group（P〈0.05）. In the field immersion test, the snail mortality by 1.6 g/m^3 LDS-SRG prepared from 5% and 10% concentrations for 72 h was 96.43% and 98.21% respectively（P〉0.05 versus the control group）. In the field spraying test, the snail mortality by 3.2 g/m^2 LDS-SRG prepared from 5% dosage for 3, 7 and 14 days was 93.99%, 91.18% and 86.48% respectively, and that from 10% dosage was 94.95%, 93.50% and 85.43%, all significantly higher than that of the control group （82.83%, 72.38% and 48.38%）（P〈0.05）; the snail mortality by 0.8 g/m2 LDS-SRG prepared from 5% dosage for 14 days（66.51%） and that by 1.6 g/m2 LDS-SRG prepared from 5% dosage for 3 days（84.61%） were both significantly higher than that by 10% LDS-SRG（20.13% and 43.06%） （P〈0.05）. Conclusion The 5% and 10% LDS-SRG used separately in the immersion test and the spraying test both meet the requirements of the national standard of Efficacy Test Methods and Evaluation of Molluscicide for Pesticide Registration.