Flight away from emergence site of wild and artificially reared olive fruit flies: effect of incoming light direction and intensity

Wild olive fruit flies flew away from the site of adult emergence, i.e. escape by direct flight from a 10 cm high, 9 cm diameter cylinder, at significantly higher percentages than artificially reared flies. This was true at both high and low light intensity. With both fly types, when the incoming light was from the cylinder top opening only (cylinder painted black) the percentage of “escaping'' flies was higher than when the incoming light was from the opening and around (transparent cylinder). The difference was significant only at low light intensity. In almost all cases a significant decrease of escape flights was observed with low light intensity.