SEX PHEROMONE-MEDIATED FLIGHT AND LANDING BEHAVIORS OF THE EUROPEAN CORN-BORER, OSTRINIA-NUBILALIS (HUBNER)

The pheromone-mediated flight and landing behaviors of male Ostrinia nubilalis were studied in a wind tunnel. The pheromone source was placed in the middle of an 18 x 18-cm horizontal surface, and a smaller surface placed 4, 18, or 36 cm downwind. The smaller surface did not appear to affect significantly the flight tracks or position of landing of males on the upwind surface, and it allowed the positions and altitudes of males as they passed over the downwind surface to be estimated. The flight altitude and position of males as they passed over the downwind surface related to where males landed on the upwind surface. Regardless of the downwind position of the downwind surface, most males flew over its center (i.e., in line with the source) and landed in line with the source on the upwind surface. When a small 2.5 x 10-cm vertical object was placed on the upwind surface, just upwind and to one side of the source, males hew over the downwind surface in positions skewed toward the vertical object and in broader distributions than for the comparable situation without an object; males landed on the upwind surface on positions skewed toward, or on, the object and with a broader distribution (laterally). Flight altitude also corresponded with landing position. Thus, when there was no vertical object, most males flew just above the downwind surface and landed on the downwind edge of the upwind surface. In contrast, with the vertical object, males flew significantly higher and tended to land past the downwind edge of the upwind surface. With a taller object (20 cm), males flew even higher, past the downwind edge and most landed on the vertical object. These data show the close relationship between Right and landing behaviors of male O. nubilalis and suggest that Right maneuvers that determine track and altitude largely govern where a male lands.