[The distribution and possible competition between Melanoides tuberculata and Tarebia granifera (Prosobranchia: Thiaridae) in Lake Hanabanilla, Cuba]. / Distribución y posible competencia entre Melanoides tuberculata y Tarebia granifera (Prosobranchia: Thiaridae) en el lago Hanabanilla, Cuba.

A study was carried out along three years, on distribution and possible competence between the two thiarid species present in Lake Hanabanilla, Cuba: Melanoides tuberculata and Tarebia granifera. Both species presented significant differences as to its abundance within a determined microhabitat, but they could match their densities for the total sampled area. These variations were mainly due to the ratio of juveniles in each species. Interaction was only detected when high abundance values were reached and some limitation resource existed (mainly in the nearest area to the shore). Both thiarids presented a high nest width, but Tarebia granifera was slightly higher; besides, this species was dominant at the end of the study at most of the sampled areas.

[The external and internal morphology of the intermediate hosts of Fasciola hepatica]. / Estudio de la morfología externa e interna de los hospederos intermediarios de Fasciola hepatica.

The main morphological traits of Fossaria cubensis and Pseudosuccinea columella, the two intermediate hosts of fascioliasis in Cuba, were studied. Differences may be seen regarding some aspects of the external morphology, as well as in the internal morphology, mainly in the reproductive system. The radular teeth have differences which are rather intangible, not allowing for their taxonomic isolation on the basis of this criterion alone. These studies suggest to take into account several criteria in order to determine the taxonomic position of each species.

[The biological control of Fossaria cubensis, the intermediate host of Fasciola hepatica, in 2 localities with different control agents]. / Control biológico de Fossaria cubensis, hospedero intermediario de Fasciola hepatica, en 2 localidades con diferentes agentes de control.

A control was carried out on Fossaria cubensis, intermediate host of Fasciola hepatica, in two localities, by means of 2 different control agents. In one of them Helisoma duryi was used due to its ecological advantages as compared with the intermediate host (higher growth rhythm and lower generational time), and in the other Tarebia granifera was used, which has biological and ecological advantages upon most mollusks (ovoviviparous, parthenogenetic, longer life cycle and higher growth rhythm). In both localities an effective control was seen with the remarkable decrease of the host density after the introduction of the competitive agent.

[A morphometric study of the juveniles of 4 populations of Tarebia granifera under laboratory conditions]. / Estudio de la morfometría de los juveniles de 4 poblaciones de Tarebia granifera en condiciones de laboratorio.

The morphometric comparison and the reproduction dynamics were carried out for newborn Tarebia granifera individuals from 4 populations of progenitors. A significantly high difference was found in the morphometry of the juveniles, which was lower in the adults. The population of the Jibacoa brook had a higher number of newborn. That indicates that his morpho is the most adequate when choosing this species as a control agent.

[The role of Marisa cornuarietis as a biological control agent and its economic and epidemiological implications]. / Rol de Marisa cornuarietis como agente de control biológico y sus implicaciones económicas y epidemiológicas.

It was determined that M. cornuarietis, a mollusk which has been used as agent for the biological control of the schistosomiasis hosts, may be a plague for rice fields. Each mollusk can consume 0.3 g of this plant in 24 hours, accounting for the destruction of 0.015 m2 of a rice field. On the other hand, it was observed that B. glabrata shows preference for the consumption of M. cornuarietis faeces. This fact favors the vector's growth and reproduction rate and at the same time decreases its mortality.

[A comparison of the growth of 2 species of Pomacea from the Antilles area useful as an agent to control tropical diseases]. / Comparación del crecimiento de 2 especies de Pomacea del área antillana, útiles como agente de control de enfermedades tropicales.

A comparative study was made on the growth of 2 Pomacea species (P. glauca and P. paludosa) of the Caribbean area. The occurrence of ecological differences reflected on the growth parameters is noted. These discrepancies may be influenced by differences in the physical-chemical and environmental status of the localities under study, but a clear-cut ecological difference between both species can be observed. Growth parameters (K and L phi), as well as the growth curves, suggest they are slow-growing species with a long life range. Differently from intermediate hosts, which are fast-growing species with a short life range, Pomacea species may keep stable populations in permanent bodies of water. It means an important advantage as biological control agents.

[The characterization of Biomphalaria orbignyi Paraense, 1974, a mollusk of medico-epidemiological importance recently reported for Cuba]. / Caracterización de Biomphalaria orbignyi Paraense, 1974, molusco de importancia médico-epidemiológica recientemente reportado para Cuba.

The conchological, anatomical and radular characteristics of Biomphalaria orbignyi are described, as well as the morphometric ratio between maximal height and maximal diameter, in which the regression coefficient value is 0.9. The life tables of Biomphalaria orbignyi shows a life range (L phi = 10.37) much higher than in the rest of the species available in Cuba; the value of k = 0.17 is similar to that of Biomphalaria havanensis. It has 2 reproductive peaks at middle age. Differently from other species of the genus, it has lower mortality at early ages and the highest peak is seen when it reaches the adult stage, which means it is a strong species. The zymograms that have been obtained confirm this species is different from B. havanensis. Since there are no marked differences on an individual basis, its correct identification requires to take into consideration every biological and ecological evidence available.