Identification of the dispersion capacity of S. ornatum late instar larvae, by artificial positioning in the upstream uninhabited sections of the stream, distant from typical breeding zones was the main objective of this study. Further more, the convenience of methylen blue vital marker application as a suitable tool in biological studies of black flies in natural environmental conditions was tested. Larval marking was performed in methylen blue aqueous solution 25 mg/l and 45 minutes exposition. High portion of visually detectible dyed larvae (about 90%) was recorded, no mortality and high persistence of the dye in the larval body all over the 15 days period.  Tendency of dispersion and successive inhabitation of downstream sections at increasing distances was expressed in majority of larvae (99,33%). The increase of distances covered in function of time was recorded, starting from 17 m to 93 m after 1 and 15 days, respectively.

Simuliidae; Simulium ornatum; dispersion; methylen blue

Presentation: oral