Molluscicidal effectiveness of Luo-Wei, a novel plant-derived molluscicide, against Oncomelania hupensis, Biomphalaria alexandrina and Bulinus truncatus

• 来源期刊: 贫困所致传染病（英文）
• 年，卷（期）: 2019,（2）
• 页码范围: 70-79
• 页数: 10页
• 语种: 英文

摘要

Background:Control of snail intermediate hosts has been proved to be a fast and efficient approach for interrupting the transmission of schistosomiasis.Some plant extracts have shown obvious molluscicidal activity,and a new compound Luo-Wei,also named tea-seed distilled saponin (TDS),was developed based on the saponins extracted from Camellia oleifera seeds.We aimed to test the molluscicidal activity of 4％ TDS against the intermediate host snails in China and Egypt,and evaluate its environmental safety to non-target organisms.Methods:In the laboratory,Oncomelania hupensis,Biomphalaria alexandrina and Bulinus truncatus were exposed to 4％ TDS,and the median lethal concentration (LC5o) was estimated at 24,48 and 72 h.In the field,snail mortalities were assessed 1,2,3 and 7 d post-immersion with 2.5 g/m3 4％ TDS and 1,3,7 and 15 d post-spraying with 5 g/m2 4％ TDS.in addition,the acute toxicity of 4％ TDS to Japanese quail (Coturnixjaponica),zebrafish (Brachydanio rerio)and freshwater shrimp (Macrobrachium nipponense) was assessed by estimations of LC5o or median lethal dose (LD5o).Results:In the laboratory,the LC5o values of 4％ TDS for O.hupensis were 0.701,0.371 and 0.33 mg/L at 24,48 and 72 h,respectively,and 4％ TDS showed a 0.33 mg/L 24 h LC5o against B.alexandrina,and a 1.396 mg/L 24 h LCs0 against B.truncatus.Across all study regions,the pooled mortalities of O.hupensis were 72,86,94 and 98％ at 1,2,3 and 7 d,following field immersion of 4％ TDS at a dose of 2.5 g/m3,and were 69,77,85 and 88％ at 1,3,7 and 15 d,following field spraying at 5 g/m2,respectively.4％ TDS had moderate toxicity to Japanese quail (7 d LD5o ＞ 60 mg/kg) and to shrimp (96 h LCs0 =6.28 mg/L;95％ CI:3.53-11.2 mg/L),whereas its toxicity to zebrafish was high (96 h LCso--0.15 mg/L;95％ CI:0.14-0.17 mg/L).Conclusions:4％ TDS is active against O.hupensis,B.alexandrina and B.truncatus under laboratory and field conditions,and it may be a candidate molluscicide of plant origin.