Competitive interactions between species of freshwater snails: I. Laboratory: Ia. General methodology

Abstract

For the development of laboratory experiments on the competitive interacitons between freshwater snail populations, special snail rooms were set up in the main building of the Research Center "Aggeu Magalhães". In the current paper, the first of a series on this subject, the general methodology of the laboratory work is described in detail. Using indoor cement channels in which a uniform seminatural environment was created, interactions of freshwater snail populations can be studied with minimal interference of the usual variables. Controlled indoor environmental techniques, as described in the current paper, may also be utilized in different types of experiments in malacology, and represent a substantial technical advance in malacological work.<br>Com a finalidade de realizar experimentos de laboratório sobre interações em populações de caramujos da água doce, salas foram especialmente preparadas para este fim no edifício principal do Centro de Pesquisas Aggeu Magalhães. Nesta publicação, a primeria de uma série sobre o assunto, é descrita, com detalhes, a metodologia geral do trabalho de laboratório. Utilizando canais de cimento foram estabelecidas condições semi-naturais sob as quais puderam ser estudadas as interações de populações de caramujos com um mínimo de interferência de variáveis ambientais. Técnicas que utilizam controle de ambiente interno, como as descritas no presente trabalho, podem ser também empregadas em muitos outros tipos de experiências em malacologia e constituem avanço substancial em trablahos malacológicos

Comparative study of the fecundity and fertility of Biomphalaria glabrata (Say, 1818) and Biomphalaria straminea (Dunker, 1848) in a laboratory through self-fertilization and cross-fertilization

“…These results confirm previous studies in laboratories by MICHELSON & DUBOIS 19 , where B. straminea was found to be more fecund than B. glabrata. B. straminea has some specific characteristics, such as vagility, aggressiveness, resistance to desiccation, high rate of locomotion and power of exploration, and great adaptability to environmental conditions 4,5,6 . Hence, all these characteristics are important if we relate them with the greater fecundity of B. straminea, explaining its greater success in the face of adverse factors.…”

“…Studies under semi-natural and field conditions have revealed the competitive superiority of B. straminea over B. glabrata 3,4,5,6,8,9 . Among the factors involved, in addition to low susceptibility to infection by S. mansoni and greater resistance to desiccation, better dispersal capacity and higher vagility were noted for the former species 6,7,14,27 .…”

The bioecology of snail vectors for schitosomiasis in Brazil

“…An alternative methodology for breeding, Biomphalaria snails has been developed, using artificial channels four meters in length, a controlled environment and continually renewed water from a natural source (Barbosa et al, 1983(Barbosa et al, , 1992. This method has made it possible to study the population dynamics of these snails, and offers obvious advantages when compared to traditional laboratory methods.…”