Growth of Biomphalaria glabrata populations in the presence of the ampullariid snails Pila ovata, Lanistes carinatus and Marisa cornuarietis.

Adults of three ampullariid species were examined for their ability to affect the population growth of Biomphalaria glabrata (M line strain) under laboratory conditions in which food (lettuce) was supplied ad libitum over an eleven week interval. Lanistes carinatus and Pila ovata were obtained from Kenya, and Marisa cornuarietis originated from the Dominican Republic. The presence of either 3 or 9 L. carinatus or 3 M. cornuarietis per 40 l aquarium did not reduce the population size of B. glabrata below levels attained in control aquaria lacking ampullariids. The presence of 9 M. cornuarietis adults significantly reduced B. glabrata populations by week 10 of the experiment. Presence of 3 or 9 P. ovata per aquarium significantly reduced B. glabrata numbers below control levels starting at week four of the experiment. Aquaria with 9 P. ovata were observed to have fewer B. glabrata egg masses than control aquaria, but the number of egg masses observed was not significantly reduced in aquaria with 3 P. ovata or with 3 or 9 L. carinatus or M. cornuarietis. However, the presence of 3 or 9 adults of each ampullariid species resulted in a significant increase in the percentage of such egg masses that disappeared prior to expected hatching date and that were presumed to have been consumed. The results of his laboratory study suggest that further investigation of the role of ampullariids as biological control agents for pulmonate snails in sub-Saharan Africa should focus on P. ovata.