[Receptivity of some Helicids frequent in Morocco to the infestation by the larvae of Protostongylids. Factors of variation (author's transl)].

Several species of Helicids common on pasture in the Rabat area were infected by a plurispecific mixture of larvae of Protostrongylids. The fecal or pulmonary origin of the larvae does not seem to influence their infective ability. The age of the larvae used for infection displays an important role on the future degree of infection of Molluscs: the young larvae are more infestive. The Helicids that were most receptive to infection are, arranged in a decreasing order: Otala lactea, Cochlicella conoidea, C. acuta and Euparypha pisana, Helicella gigaxii. O. lactea and E. pisana permitted the development of Muellerius capillaris, Cystocaulus nigrescens and Neostrongylus linearis. The former species of Helicid is a new intermediary host. The two species of Cochlicella were not suitable for M. capillaris. The Helicids ensure the quantiative and specific regulation of the infection of the Ovines.