秀山海泥浸液对人体蠕形螨的杀灭作用

Acaricidal Activities of the Water Extract of Xiushan Sea Mud against Human Demodex Mites

目的观察秀山海泥浸液体外杀灭皮脂蠕形螨和毛囊蠕形螨的作用。方法用改良刮压法取人体皮脂蠕形螨和毛囊蠕形螨,每份标本含运动活泼的蠕形螨30条以上,均匀涂抹于滴加200μl海泥浸液(浓度分别为2.5、2.0、1.5、1.0和0.5kg/L)的载玻片上,10%硫磺乳乳浊液为阳性对照,生理盐水为空白对照,各组实验同时进行;在20℃,相对湿度70%条件下,分别于5min、10min、20min、40min、1h、2h、4h、8h、12h和24 h记录虫体死亡情况,镜下观察蠕形螨的活动度及其形态。结果 1.0～2.5kg/L的秀山海泥浸液可使两种蠕形螨活动加剧,皮脂蠕形螨皱缩变形、扭动、虫体变短,毛囊蠕形螨足体中央消化管收缩,尾部呈现较快频率的伸缩运动。浓度由2.5kg/L降至1kg/L时,皮脂蠕形螨和毛囊蠕形螨的活动活跃度比例分别由79.4%(27/34)、65.7%(23/35)降至68.9%(26/38)、53.8%(21/39),活跃时间分别由15min、20min延长至100min、104min。0.5kg/L的海泥浸液对两种蠕形螨的形态与活动度无明显影响。当秀山海泥浸液浓度由2.5kg/L降至1.5kg/L时,两种蠕形螨的全部死亡时间均由2 h延长至8h。1kg/L的秀山海泥浸液对皮脂蠕形螨的杀灭率高于阳性对照组(P<0.05),而对毛囊蠕形螨的杀灭率与阳性对照组相比差异无统计学意义(P>0.05)。当浓度降低至0.5 kg/L时,对皮脂蠕形螨和毛囊蠕形螨的杀灭率明显降低,与空白组相比差异无统计学意义(P>0.05),两种蠕形螨的最低有效浓度均为1kg/L。皮脂蠕形螨和毛囊蠕形螨1h的LC_(50)值(半致死浓度)分别为1913mg/L与2131mg/L。结论秀山海泥浸液具有杀灭两种人体蠕形螨的作用,对皮脂蠕形螨的杀灭作用略强于毛囊蠕形螨。

Objective To observe the acaricidal effect of the water extract of Xiushan sea mud on ,Demodex brevis and D.folliculorum. Methods D. brevis and D.folliculorum were obtained with modified scraping method. Each sample contained 30 or more alive Demodex which were evenly spread on the slides with 200 p.1 water extract of Xiushan sea mud at a concentration of 2.5, 2.0, 1.5, 1.0 and 0.5 kg/L, respectively. With 10% sulfur emulsion as positive control and saline as blank control, each experiment group was carried out at the same time. Under room temperature of 20 ~C and relative humidity of 70%, parasite death number was recorded at 5min, 10rain, 20rain, 40min, 1 h, 2h, 4h, 8h, 12b and 24 h. The acaricidal rate was measured and calculated by counting method. Demodex activity and morphology were observed using microscope. Results 1.0--2.5 kg/L of the water extract of Xiushan sea mud increased the activities of both kinds of Demodex. D. brevis showed shrinkage, deformation, twisting and the bodies became shorter. The digesting vasoconstrictions of D.foUiculorum also shrank and the stretching frequency of the tails moved faster. When the concen- tration of the sea mud extract decreased from 2.5 kg/L to 1 kg/L, the proportion of active movement of D. brevis and D.fol- liculorum decreased from 79.4% （27/34）, 65.7% （23/35） to 68.9% （26/38）, 53.8% （21/39） , and the activity time extended from 15 min, 20 min to 100 min, 104 min, respectively. The 0.5 kg/L of the sea mud extract showed no sig- nificant effect on the morphology and activity of both species of Demodex. When the concentration decreased from 2_5 kg/L to 1.5 kg/L, the time to kill both Demodex spp. extended from 2 h to 8 h. The extract at a concentration of 1 kg/L showed higher acaricidat effect to D. brevis than that of positive control （P〈0.05） , while there was no significant difference for D.folliculorum （P〉0.05） . When the concentration decreased to 0.5 kg/L, the acaricidal effect for D. brevis and D.folliculorum remarkably reduced and there was no significant difference with the control groups （P〉0.05） . The lowest effective concentration for both Demodex spp. was 1 kg/L. The values of 1 h median lethal concentration （LC50） of the sea mud extract for D. brevis and D. foUiculorum were 1 913 mg/L and 2 131 mg/L, respectively. Conclusion The water extract of Xiushan sea mud shows acaricidal effect to human Demodex. The effect to D. brevis is slightly better than to D. folliculorum.