Antennal mechanosensors mediate sex pheromone‐induced upwind orientation in the potato tuberworm moth

Males of the potato tuberworm moth Phthorimaea operculella (Lepidoptera: Gelechiidae) locate conspecific females by a series of short and straight flights, or ‘hops’. On the floor of a wind tunnel, P. operculella can change their heading angles in response to wind direction shift, suggesting that they detect wind direction and orient upwind when on the ground. It is unlikely that they navigate in wind by vision‐induced optomotor anemotaxis as in many flying moths. To investigate the mechanism of wind direction detection in this species, their orientation behaviour in response to pheromone pulses is observed in a wind tunnel. Intact male moths orient upwind even in complete darkness. After the flagellum of one antenna is amputated, male moths still successfully orient upwind. However, they fail to head upwind when the basal segments of both of their antennae are immobilized with glue. The ability to surge upwind is restored by removing the glue from the antennae. Thus, the results of the present study indicate that males of P. operculella orient upwind in response to mechanoreceptive cues from mechanosensory organs on their antennae. In Lepidoptera, two distinct anemotactic mechanisms of different sensory modalities appear to coexist: optomotor anemotaxis when airborne and the aim‐then‐shoot anemotactic system mediated by antennal mechanoreception when on the ground.