Extraordinary feeding behaviour in Diptera Sciomyzidae, snail-killing flies

In the laboratory, the larva of Sepedonella nana, Diptera Sciomyzidae, were only able to develop at the expense of small aquatic oligochets collected in adult habitats. Up till now, larval cycles have been elucidated for 38% of the Sciomyzidae; all these larvae proved to be strict consumers of aquatic or terrestrial molluscs (including slugs). This specific predation was considered as a major distinguishing characteristic of Sciomyzidae among Diptera. The unusual nutritional behaviour of S. nana reported in the present note is in contradiction with well-established prior knowledge. The species presented all the characteristics of the family, particularly the ventral arch sclerite present on the larva cephalopharyngeal skeleton. It was considered as a derived species; this behaviour, probably of secondary type, revealed new nutritional types for Afrotropical Sciomyzidae for which the biology of only five species was elucidated out of about 60 species described.