Effect of temperature on the reproduction of the snail biompholaria glabrata

1. The reproduction of the snail Biomphalaria glabrata, one of the intermediate hosts of Schistosoma mansoni, was evaluated under laboratory conditions by measuring egg production, number of ovipositions, number of eggs per oviposition, and hatching rate using a Latin square design with five different temperature treatments. This permitted the elimnation of occasional variation in oviposition due to manipulation or a priori group. 2. Egg production and spawning rates were higher at temperatures between 20.0 and 27.5-C than at 17.5-C. Number of eggs per spawning and hatching rate did not vary with temperature. 3. During a 3-day adaptation phase, a short-term therminal effect appeared in chich some indices of reproductive rates differed signifcantly from those of the experimental phase

Influence of experimental illumination and seasonal variation on crossbreending mating in the snail Biomphalaria

The crossbreeding activities of the Schistosoma mansoni vector snail Biomphalaria glabrata were counted in a laboratory aquarium throughout the year under two regimes of 12h light: 12h dark from 7 A., M. to 10 P. M. Mating increased significantly in Authmn and Winter and just missed a significant inverse correlation with temperature and a direct one with locomotion. Other similar experiments were carried out to compare mating under various ilumination conditions in complete daily cycle measurements. Mating counts decreased under the regimes which submited snail to a total exposure of 12h light and 12 dark during a daily cycle in the following sequence: 12h light: 12h dark alternating hourly with light gradient, 12h light: 12h dark, 1h light: 1h dark and 12h dark: 12h light. Under two constant illuminations, the mating scored less than under the previous conditions, except under 12h light. Under darkeness the mating count was lower than light conditions. There was no way to differentiate the night and day rhythms of mating on different days in each regime, except for mating under 12h light: 12 dark alternating with light gradient, constant dark and 12h dark: 12h light conditions. Mating increased in certain light and temperature conditions, in wich the intensities, should have an optimum value

The effect of seasonal temperature and experimental illumination on reproductive rate in the snail Biomphalaria glabrata

1. Reproduction in the snail Biomphalaria glabrata, a vector of Schistosoma mansoni, was measured by egg production and other paramneters such as number of clutches, eggs per clutch and egg hatching, under laboratory conditions. 2. Reproductive rates were highest in terms of total number of eggs, clutches and hatching under constant illumination, followed by conditions similar to the natural rhythm of illumination. The greatest reduction in reproduction occurred in constant darkness. in summary, reproductive rate was dependent on both the intensity of absolute illumination and the schedule of illumination exposure. 3. Seasonal variation in reproductive rate appeared to vary inversely with local temperature in Belo Horizonte, situated in a tropical zone (latitude 20 S) owing probably to a temperature prefernce of 20 to 25-C by the snail. the highest reproductive rates occurred in winter, except for the parameter eggs per clutch which was maximal in autumn. Snail reproduction appeared to be most reduced during summer. There was no linear correlation between reproductive rate and temperature