Virgin homozygous black pigmented and albino Biomphalaria glabrata are paired during a period varying from 1 to 20 days. The rate of cross-fertilized parents is statistically similar for the various lengths of pairing. As a whole, nearly 80% of the albino snails produce a pigmented progeny. This production begins as soon as the snails are mated and continues after their separation. To measure the actual use of the allosperm, its use during the postmating period must be added to the length of mating. So, it appears that the real use of the allosperm is statistically constant (mean slightly inferior to 8 weeks) and not related to the length of the previous pairing.

Un essai de contrôle biologique de Biomphalaria glabrata a été réalisé en Guadeloupe à l'aide de Ribeiroia marini guadeloupensis Nassi, 1978, Trématode autochtone qui stérilise le Mollusque vecteur de Schistosoma mansoni. L'essai s'est déroulé dans une mare dont la population de B. glabrata présente un cycle démographique annuel lié à l'alternance saison sèche-saison humide. Environ 8 millions d'oeufs de R. marini ont été introduits en 15 mois dans la mare. Malgré le faible rendement de ces introductions, dû notamment à la forte turbidité de l'eau, cet essai a été positif puisqu'il s'est soldé par la disparition de la quasi-totalité des Mollusques. L'analyse des résultats concernant l'évolution des effectifs de B. glabrata et l'évolution de la prévalence montre qu'une efficacité comparable pourrait être obtenue par des déversements d'oeufs limités dans le temps mais massifs.

Experimental study of the life history of Echinostoma parvocirrus n. sp. (Trematoda: Echinostomatidae), a larval parasite of Biomphalaria glabrata in Guadeloupe.SUMMARY. The larval stages and adult of a new species of Echinostome with 37 collar spines originating from Guadeloupe are described. The first intermediate host is the snail vector of Schistosoma mansoni in this island, Biomphalaria glabrata. Metacercariae encyst in the pericardial sac of the same snail and the physid snail Physa marmorata, as in kidneys of tadpoles of Bufo marinus. Adult develops experimentally in ducklings of Cairina moschata and in canaris but not in ducklings of Anas platyrhyncos, pigeons, chicks, albino mice, Ratlus rattus, or wild and albino R. norvegicus. The natural final host is unknown.

When one pigmented Biomphalaria glabrata is mated with 1 to 20 albino snails, the percentage of albino parent producing pigmented offspring decreases while the percentage of parent laying albino offspring increases. If the number of snaisl/group increases, the mean duration of the use of allosperm decreases.

RÉSUMÉ. Quatre furcocercaires émises par On four furcocercous cercariae obtained from Biomphalaria glabrata in Guadeloupe.SUMMARY. For furcocercous cercariae obtained from Biomphalaria glabrata in Guadeloupe are described. Two belong to the family Strigeidae, one being characteristic of the genus Apharyngo strigea, the other, named Cercaria parvisglandulis n. sp., being a new type in this family. The third one is characteristic of the sub-genus Tylodelphys of the family Diplostomatidae. This cer caria penetrates the cichlid fish Tilapia mossambica and develops to diplostomulum in the eye vitreous body. The fourth one is a large size ocellate schistosomatid cercaria closely resembling Trichobilharzia cercaria. The chaetotaxy of the latter is reported and compared with those known in the genera Trichobilharzia and Gigantobilharzia. Their relationships with adult Trematodes reported from Guadeloupe and neotropical adjacent areas are discussed.