Authors Yung-san Liang, Mei-Shei Su, Laksiri Karunaratne, and Fred Lewis
Overview and recommendations
For the most part, Bulinus truncatus truncatus snails grow well under the same conditions as those described for Biomphalaria spp. snails. There are a few differences which are important to consider when working with B. t. truncatus.
· The egg clutches laid by adult Bulinus snails are smaller than those laid by B. glabrata, and there will be fewer embryos within each egg clutch. Typically, 20 or fewer embryos are contained within the Bulinus egg clutches, compared to 30 or more embryos for many of the B. glabrata egg clutches.
· Growth of Bulinus, measured by the time to reach maturity, is usually slower than of B. glabrata.
· The optimal size of B. t. truncatus snails exposed to S. haematobium miracidia is around 2-3 mm in diameter, whereas for exposure of B. glabrata to S. mansoni, optimal size is around 5-7 mm in diameter.
· The number of S. haematobium cercariae one can obtain at any one time from one Bulinus t. truncatus snail (300-500) is considerably lower than the number of S. mansoni cercariae obtained from one B. glabrata snail during its lifetime (2000-4000), all conditions being equal.
· The headfoot surface (upon which it crawls) of B. t. truncatus, in relation to its total body size, is substantially greater than that of B. glabrata. B. t. truncatus snails adhere to solid surfaces more firmly than do B. glabrata. These differences have practical consequences when handling the two snail species with forceps and when cleaning their aquaria. B. glabrata can be dislodged easily from hard surfaces (tank, tray or lettuce, etc.) with small forceps, whereas attempting to dislodge Bulinus t. truncatus in the same way can result in damage to the body of the snail if it is not done carefully. The direction in which force is applied with forceps to lift B. t. truuncatus from a surface is important. Envisioning the snail’s moving from a South to North direction, one should gently tilt the shell from the right (East) to the left (West), then gently lift the snail in a westerly direction. Otherwise, damage to the body of the snail may occur, as evidenced by bleeding into the water.
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.