Drift and activity responses of black flies (Simulium vittatum) in the field: influences of tactile and injury-released stimuli from simulated predation

Abstract

Prey must manage threat from many types of predators; therefore, selection should favor sensory mechanisms that allow the refinement of defensive behavior. To assess responses to tactile and chemical stimuli related to predation, we observed drift and activity of larval black flies (Simulium vittatum) to simulated predator contact intended to imitate benthic and drift predators as well as a combination of tactile and injury-released stimuli. In the field, larvae responded to tactile stimuli applied to the head with a higher frequency of curling and posterior abdominal segments with a higher frequency of drifting. Additionally, chemical cues from injured conspecifics followed by tactile stimuli applied to the head resulted in a higher frequency of drifting than to either cue independently and this effect was more pronounced at night. The results of our study indicate that larval black flies may utilize multiple cues to determine their antipredator and predator avoidance strategies.