Molecular Characterization of Rotifers and Their Potential Use in the Biological Control of Biomphalaria.

Datao Lin,Suoyu Xiang,Zhongdao Wu,Benjamin Sanogo,Yousheng Liang,Xi Sun

doi:10.3389/fcimb.2021.744352

Abstract

BackgroundSchistosomiasis is one of the most important tropical parasitic diseases worldwide. Biomphalaria straminea, the intermediate host of Schistosoma mansoni, has invaded and spread to Southern China since 1974 and may pose enormous threats to public health. Controlling intermediate host snails is an effective strategy in schistosomiasis intervention. However, the only effective chemical molluscicide, niclosamide, currently recommended by WHO may cause environmental pollution, loss of biodiversity, and high costs. Thus, to counter intermediate hosts, a sustainable and environmentally friendly tool is urgently needed. Here, we conducted field investigations to collect and identify a potential snail competitor rotifer and evaluated its molluscicide effect.ResultsIn this study, we collected two samples of rotifers from Shenzhen. We found both red and black phenotypic B. straminea snails at the sampling sites. We identified the rotifer population as a species of the genus Philodina according to the amplification and phylogenetic analysis results of coxI gene. We found that rotifer exposure did not significantly affect the hatching rate of B. straminea eggs but promoted the killing of juvenile snails. Meanwhile, rotifer exposure did not significantly alter the fecundity of B. straminea quantified by the number of eggs per egg mass, the number of egg masses per snail, and the number of eggs per snail; but the snails exposed to rotifers showed lower fecundity performance than the control snails. Importantly, rotifer exposure could significantly affect the development of juvenile B. straminea, showing a smaller shell diameter of the exposed snails than that of the control snails. In addition, rotifer exposure affected the life span of B. straminea snails, showing a 16.61% decline in the average life span. After rotifer exposure, the S. mansoni-infected B. straminea snails died significantly faster than those without rotifer exposure. Similar findings were observed in S. mansoni-infected Biomphalaria glabrata snails. These results implied that rotifer exposure significantly promoted the mortality of S. mansoni-infected B. straminea and B. glabrata.ConclusionsOur study demonstrated the potential molluscicide effect of rotifers on intermediate hosts under laboratory conditions. Our findings may provide new insights into the development of biocontrol strategies for snail-borne disease transmission.

Highlights

Schistosomiasis is one of the most important human parasitic diseases (Chitsulo et al, 2000), causing almost 240 million people infected worldwide, which may cause huge economic and social burdens globally (Colley et al, 2014)
We found that some rotifers were attached to the surface of the shell of Biomphalaria snails in field studies
We found that the rotifers were mainly attached to the navels of Biomphalaria snails (Figure 2A)

Summary

Introduction

Schistosomiasis is one of the most important human parasitic diseases (Chitsulo et al, 2000), causing almost 240 million people infected worldwide, which may cause huge economic and social burdens globally (Colley et al, 2014). As an important intermediate host of S. mansoni (Coelho and Caldeira, 2016), the freshwater snail B. straminea has invaded Hong Kong, China, since 1974 and has spread widely in South China (Meier-Brook, 1974; Lin et al, 2020). This invasive snail can transmit the zoonotic parasite Angiostrongylus cantonensis (Xu et al, 2019; Zhu et al, 2019). We conducted field investigations to collect and identify a potential snail competitor rotifer and evaluated its molluscicide effect

Methods

Results

Conclusion