Effects of Helleborus thibetanus extract, a novel plant-derived molluscicide on Oncomelania hupensis, the intermediate host of Schistosoma japonicum

The snail, Oncomelania hupensis, is the only intermediate host of Schistosoma japonicum. Thus, snail control is one of the most rapid and effective strategies for disrupting schistosomiasis transmission. In this study, 125 botanical extracts were screened for molluscicidal activity, leading to the selection of the extract of Helleborus thibetanus (EHT) for further evaluation. EHT exhibited strong molluscicidal activity against O. hupensis (LC50 value of 12.54 mg/L and LD50 value of 1.400 g/m2). In field trials, an EHT dose of 10 g/m2 killed 85.19% of the snails. Histopathological evaluation revealed that EHT caused comprehensive damage to the cephalopodium, gill, salivary gland, stomach, and hepatopancreas. Importantly, EHT was also generally safe for non-target organisms, such as Danio rerio, Daphnia magna, Pelophylax nigromaculatus, Cipangopaludina chinensis, and Neocaridina denticulata at the test concentration. These results suggest the potential of EHT as an effective and eco-friendly molluscicide for the control of O. hupensis.