Surveys for natural host plants of mansonia mosquitoes inhabiting “toh daeng” peat swamp forest, narathiwat province

Abstract

The surveys were carried out monthly during April to Octorber, 2002 and examined 68 sampling sites around “Toh Daeng” peat swamp forest, Narathiwat Province of which 38 were known Mansonia-positive habitats and 30 were Mansonia-negative sites. The present larval surveys were just qualitative one owing to host plants characteristics (location, distribution and abundance), difficulties in locating and selecting the host plants in the swamp forest and time constraints. The attempts to search for host plants were more than 20 times for each plant species until the larvae were found. The confirmation of the presence of Mansonia larvae on each plant species was 6 times on different plants and locations. The larvae of Ma. bonneae and Ma. uniformis were obtained form eighteen plant species (10 families) namely Metroxylon sagu, Melaleuca cajuputi, Pandanus militaris, Pandanus immerses, Hanguana malayana, Typha angustifolia, Hymenachne acutigluma, Scirpodendron ghaeri, Scleria sumatrensis, Rhynchospora corymnosa, Sacclolepis indica, Cyperus babakan, Chyperus corymbosus, Lepironia articulata, Leersia hexandra, Eichorrnia crassipes, Pistia stratriotes and ferns. The aquatic plants – S. ghaeri, S. sumatrensis, H. acutigluma, R. corymnosa, S. indica, C. babakan, C. corymbosus, L. articulata were the common host plants. Samples from larger trees, M. sagu and M. cajuputi yielded only low number (1-7) larvae per scraping. Ma. uniformis was recovered from most of the host plants, however, Ma. bonneae preferred submerged plants and was not collected from floating aquatic plants, E. crassipes and P. stratriotes. The description of modified dipper and dipping technique were given and discussed.