Authors Yung-san Liang, Mei-Shei Su, and Laksiri Karunaratne

Introduction

Oncomelania hupensis ssp. cultures are kept under 24-hour lighting conditions. Oncomelania hupensis ssp. snails are not hermaphroditic, so males must be mixed with females to obtain viable eggs.

Equipment

Suitable shallow plastic pans (or aquaria) for maintenance of snails

Glass lids for snail containers

Materials and reagents

Aged tap water

Petri dish of algae/mud

Petri dish of diatoms

Children’s clay

Oncomelania hupensis ssp. snails (20-30 pairs [male + female])

Procedure

·         In a shallow pan containing the equivalent of one petri dish of algae and one petri dish of diatoms, add water to about 1” depth.

·         Add 20-30 pairs (male + female) of adult Oncomelania snails (the outer lip of the shell [varix] is usually thickened in sexually mature snails).

·         One must first determine the sex of each snail to ensure an even distribution of males and females. Size alone is not a practical way to determine the sex of these snails, since both sexes of O. h. hupensis, O. h. nosophora, and O. h. formosana are about the same size (around 8 mm length) when they are fully grown.  O. h. quadrasi full-grown males (around 5 mm length) are only slightly smaller than full-grown females (6 mm).

·         The best way to distinguish a male from a female Oncomelania is to look for the presence of a verge (penis). With the adult snail in a horizontal position, insert the apex in children’s clay that has been attached to the inside rim of a petri dish. The snail’s operculum should be facing up.

·         Flood the petri dish with water. Once the head of the snail extends, place the petri dish under a dissecting microscope to identify the verge (Photo), which presents as a structure situated between the mantle collar and the neck of the snail, but may not extend past the shell opening.

 

 

Follow-up comments/recommendations

The lifespan of uninfected Oncomelania hupensis ssp. in the laboratory is 1-2 years under optimal conditions. With all 4 subspecies listed here, snail pairs will produce the greatest numbers of eggs for about the first 6 months after they mature, after which egg production begins to diminish.

 

During their lifespan, many Oncomelania crawl onto the lid of the container and hang there indefinitely. This is normal behavior, since they are amphibious in nature. Hanging snails should be removed and placed back into the water when the containers are routinely changed (there is no need to do so more frequently).

 

References

Bruce, J.I., Radke, M.G., and Davis, G.M. 1971. Culturing Biomphalaria and Oncomelania (Gastropoda) for large-scale studies of schistosomiasis. Biomedical Report No. 19, 406th Medical Laboratory, U.S. Army.

 

Liang, Y-S., Bruce, J.I., and Boyd, D.A. 1987. Laboratory cultivation of schistosome vector snails and maintenance of schistosome life cycles. Proceedings of the First Sino-American Symposium 1: 34-48.

 

Tucker, M. S., Karunaratne, L. B., Lewis, F. A., Frietas, T. C., and Liang, Y-S. 2013. Schistosomiasis, in Current Protocols in Immunology 19.1.1-19.1.57, John Wiley and Sons, Inc., (R. Coico, Ed).  Published online November 2013 in Wiley Online Library (wileyonlinelibrary.com). doi: 10.1002/0471142735.im1901s103.