RECEPTIVITY OF SOME HELICIDS FREQUENT IN MOROCCO TO THE INFESTATION BY THE LARVAE OF PROTOSTONGYLIDS - FACTORS OF VARIATION

Several helicid species 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 did not influence their infective ability. The age of the larvae used for infection displayed an important role on the future degree of infection of mollusks; the young larvae were more infective. The helicids most receptive to infection in decreasing order were, 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. O. lactea is a new intermediary host. The 2 Cochlicella spp. were not suitable for M. capillaris. The helicids ensure the quantitative and specific regulation of the infection of the ovines.