FACTORS INFLUENCING DISPERSION OF LARVAL BLACK FLIES (DIPTERA, SIMULIIDAE) - EFFECTS OF THE PRESENCE OF AN INVERTEBRATE PREDATOR

Laboratory experiments were conducted to study aggregative responses of larvae of Simulium vittatum Zetterstedt on a ceramic tile to activity of a predatory perlid stonefly, Claassenia sabulosa (Banks). Nearest-neighbor analysis indicated that larvae became aggregated regardless of whether a predator was present. There was no significant difference in either number of larvae remaining on the tile or degree of black fly aggregation between trials that lacked a predator and those in which a stonefly could travel over the tile. Direct contact between predator and prey caused single simuliid larvae to release from the substrate, but daytime black fly behaviour was otherwise unaffected by stonefly activity.