BIOLOGY OF DASYHELEA KIEFFER FROM DRAINS AND MONKEY CUPS (DIPTERA : CERATOPOGONIDAE)

Abstract

The biology of Dasyhelea Kieffer from drains and monkey cups is studied. Some taxonomic work on the new species and an attempt at colonising a drain inhabiting species are carried out. Drain habitats are sampled from the National University of Singapore at Kent Ridge and Primary Production Department's Demonstration Farm in Lim Chu Kang. Monkey cups are obtained from Kent Ridge's 'Adinandra belukar'. All immature stages are reared on their native food substrates. Results reveal seven species of Dasyhelea; four are possibly new, and from drains. Three others are from pitchers. Each stage of the life cycle between the two habitat species is biologically and morphologically different. The life cycle duration of pitcher Dasyhelea is more than twice that of drain Dasyhelea. Survival rate to adult is dependent on food substrates in the latter but not former. All females from pitchers are gravid within 24 hours of emergence; those from drains require either a proteinaceous or sucrose diet, depending on larval nutrition, in order to develop the first batch of eggs. Mouthparts of both sexes from both habitats suggest that the proboscis is not used for biting but is modified for nectarophagous or phytophagous habits. In conclusion, it appears that a different survival strategy is adopted by the two groups of Dasyhelea: each is beneficial to its survival in its habitat.