INTRODUCTION: ecological studies were carried out on mollusk populations of medical and veterinary importance with emphasis on Fasciola hepatica intermediary hosts species. OBJECTIVES: to determine the relative abundance of populations and the possible use of some species as biological control agents against F. hepatica intermediary hosts. METHODS: a total of 13 freshwater bodies were sampled during March and November, 2008 using Capture by effort unit method to capture the mollusks RESULTS: thirteen mollusk species (12 gastropods and 1 bivalve) were found after sampling. The relative abundance of species varied in different types of habitat. The intermediary host species of fascioliasis were dominant in two sites. Fossaria cubensis was dominant in Canal de la Entrada despite the presence of Melanoides tuberculata. The specie Pseudosuccinea columella was more abundant in Los Mangos. In La Presa del Matadero y Las Palmas despite the presence of these species, the prevailing ones were Physa acuta and some planorbids. CONCLUSIONS: the sites where intermediary hosts of Fasciola hepatica predominated were identified through data on the distribution and relative abundance. In some sites Melanoides tuberculata was present and acted as a biological control agent but it did not in others. Therefore, an evaluation on using a different thiarid would be useful to control these species.

INTRODUCCIÓN: se realizaron estudios ecológicos sobre las poblaciones de moluscos de importancia médico-veterinaria con énfasis en las especies hospederas de Fasciola hepatica. OBJETIVOS: determinar la abundancia relativa de las poblaciones, así como el posible uso de algunas especies competidoras en el control biológico de hospederos intermediarios de Fasciola hepatica. MÉTODOS: se muestrearon 13 cuerpos de agua dulce durante el período marzo-noviembre de 2008 utilizando el método de captura por unidad de esfuerzo para la colecta de los moluscos. RESULTADOS: por medio de los muestreos se identificaron 13 especies de moluscos dulceacuícolas pertenecientes a las clases Gastropoda (12) y Bilvalvia (1). Las abundancias relativas de las especies presentaron variaciones según el tipo de hábitat. Las especies hospederas intermediarias de fasciolosis predominaron en 2 de los sitios de muestreo. Fossaria cubensis fue dominante en la localidad del Canal de la Entrada, a pesar de estar presente Melanoides tuberculata, posible control biológico. Pseudosuccinea columella fue más abundante en la localidad de Los Mangos. En La Presa del Matadero y Las Palmas, a pesar de estar presente estas especies, las que predominaron fueron Physa acuta y algunos planórbidos. CONCLUSIONES: se identificaron los sitios donde están presentes los hospederos de Fasciola hepatica, con datos de su distribución y abundancia relativa. En algunos sitios Melanoides tuberculata actúa como control biológico y en otros no, por lo que habría que evaluar el uso de otros tiáridos para poder controlar estas especies.

INTRODUCTION: in Cuba, recent studies with colophony - a resin from Pinus caribaea and P. tropicalis - have shown its molluscicidal activity on Biomphalaria havanensis, intermediate host of schistosomosis. OBJECTIVE: to determine the impact of colophony on the heart activity and the hatching of B. havanensis eggs in lab. METHODS: lethal doses of colophony (LD50 y LD90) were used to determine their effect on heart activity and their ovicidal capacity on B. havanensis eggs. Heartbeats were counted using stethoscope. The ovicidal effect was observed in one day and 5-day laid eggs. RESULTS: as a result, this product had an impact on the embrionary development of one-day and five-day eggs; the latter were the least affected. In addition, a marked reduction in the number of heartbeats per minute was observed. CONCLUSION: colophony may be considered as possible option for control of B. havanensis because of their molluscicidal properties.

INTRODUCCIÓN: estudios recientes en Cuba con colofonia, resina extraída a partir de Pinus caribeae y Pinus tropicalis, han demostrado su actividad molusquicida sobre Biomphalaria havanensis, hospedero intermediario de esquistosomosis. OBJETIVO: determinar la influencia de la colofonia sobre la actividad cardiaca y sobre la eclosión de los huevos de B. havanensis en condiciones de laboratorio. MÉTODOS: se trabajó con las dosis letales (DL50 y DL90) de colofonia, para determinar su influencia en la actividad cardiaca y su carácter ovicida en huevos de B. havanensis. RESULTADOS: como resultado se obtuvo que este producto afecta el desarrollo embrionario de los huevos de 1 y 5 d de puestos, y estos últimos son los menos afectados. Además, se observó una marcada disminución en el número de latidos del corazón por minuto. CONCLUSIÓN: la colofonia puede considerarse como un posible candidato para el control de B. havanensis, por causa de su evidente carácter molusquicida.

The variation of abundances of intermediate snail hosts of Fasciola hepatica in Cuba (Fossaria cubensis and Pseudosuccinea columella) was studied during one year under natural conditions at five sampling sites in San Juan y Martinez municipality, Pinar del Rio province, Cuba. The effect of some environmental variables on the lymnaeid abundances was also studied. A canonical correspondence analysis showed that both species do not generally occur together in the same habitat and that most factors affect them in an opposite fashion, although both of them correlate positively through time to the diversity of the habitats. F. cubensis prefers the sites that are in or closer to the city whereas P. columella is more abundant in rural sites. Lymnaeid abundances are mainly affected by nitrite and nitrate concentrations as well as by the abundance of the thiarid Tarebia granifera. F. cubensis is more abundant in polluted habitats with low densities (or absence) of T. granifera whereas P. columella prefers cleaner habitats and can coexist with the thiarid, even at its higher densities. The implications of divergent preferences of the two lymnaeids for the control of fasciolosis are discussed.

A snail-conditioned water experiment was conducted in Pseudosuccinea columella to test the possible role of a chemical interaction between snails on the diminished growth and fecundity rates found for snails raised in pairs compared to those raised in complete isolation. The results permit to discard the hypothesis of an inhibition of growth and reproduction between snails due to factors released into the water.