Population dynamics of snail Lymnaea rubiginosa in rice fields and its infection with larvae of trematodes in the subdistrict of Surade, West Java [Indonesia]

anglais. Rice field of irrigated paddy was the most suitable habitat as breeding site of snail Lymnaea rubiginosa, the intermediate host of Fasciola gigantica and other trematodes. Fluctuations in the population of fresh water snail, L. rubiginosa in irrigated rice field and their infection with F. gigantica and other trematodes were studied in five villages in the subdistrict of Surade, province of West Java. Snails were sampled based on time collection (half an hour) each site of collection. The samples of the snails were further counted and examined for the presence of larval trematodes. The result indicated that snails died during the dry season except those in persistent aquatic refuges such as streams and springs. Surviving snails recolonised rice fields near villages by passive transfer with water from refuges early in the wet season. Some recolonisation may also have resulted from hatching of snail eggs deposited in habitats which had not been dried for more than a few weeks. Recolonisation with snails of further rice fields from a village occurred during the later period of the wet season. No snail infected with F. gigantica was found in the distance of more than 200 m from a village. Snails with the highest prevalence of infection occurred in rice fields which received effluent from a cattle pen or were fertilised with bovine faeces. Each snail was only infected with one species of trematode. Infection with echinostome larvae was most common

inconnu. Lahan sawah padi irigasi merupakan habitat yang sangat cocok untuk perkembang-biakan siput Lymnaea rubiginosa yang merupakan induk semang antara cacing Fasciola gigantica dan trematoda lainnya. Fluktuasi populasi siput Lymnaea rubiginosa di sawah padi irigasi dan infeksinya dengan larva F. gigantica dan trematoda lainnya telah diteliti di lima desa di Kecamatan Surade, propinsi Jawa Barat. Siput disampel berdasarkan waktu, yaitu 30 menit-orang setiap lokasi. Selanjutnya, siput dihitung dan diperiksa terhadap adanya larva cacing trematoda. Hasil penelitian menunjukkan bahwa sebagian besar siput mati pada musim kemarau, kecuali yang tinggal di sisa-sisa genangan air seperti selokan dan mata air. Siput yang masih hidup ini akan tersebar lagi di sawah padi di sekitar pemukiman dengan cara pasif bersamaan dengan aliran air dari selokan pada awal musim penghujan. Rekolonisasi siput juga terjadi dari menetasnya telur-telur siput yang berada di habitat yang mengalami kekeringan tidak lebih dari beberapa minggu. Rekolonisasi siput di lahan sawah padi yang jauh dari pemukiman terjadi lebih belakangan dari musim penghujan. Tidak ditemukan siput terinfeksi oleh F. gigantica pada lahan sawah berjarak lebih dari 200 m dari pemukiman penduduk. Prevalensi tertinggi infeksi Fasciola ditemukan pada siput di sawah yang mendapat limpahan kotoran dari kandang ternak atau yang dipupuk dengan kotoran sapi/kerbau. Ternyata dalam satu siput hanya ditemukan infeksi oleh satu jenis larva cacing trematoda. Infeksi oleh Echinostoma pada siput kejadiannya paling umum