Meeting Abstract

17.9  Friday, Jan. 4  Antennal positioning in flying hawk moths KRISHNAN, A.*; SANE, S.P.; National Centre for Biological Sciences, TIFR, Bangalore; National Centre for Biological Sciences, TIFR, Bangalore anandk@ncbs.res.in

Insects of diverse orders display forward positioning of the antennae at the onset of flight. Because antennal mechanosensory feedback is important for flight control, proper positioning of the antennae may be of critical importance for the acquisition of these inputs during flight. We investigated the neural mechanisms of antennal positioning in the hawk moth Daphnis nerii. Our results indicate that the mechanosensory Bohm’s bristles on the antennal scape and pedicel are the primary mediators of positioning of the ipsilateral antenna. Ablation of these mechanosensors results in mis-positioning of the antennae and frequent collisions between the antennae and wings. The antennal motor neurons respond to stimulation of the Bohm’s bristles at very rapid latencies, suggesting that the underlying sensorimotor connections are probably monosynaptic. Moreover, we found that the antennal muscles of hawk moths also received visual inputs from both ipsilateral and contralateral eyes. However, the response latencies to visual stimuli were longer than those to stimulation of the Bohm’s bristles. Our results thus suggest that antennal positioning behaviour constitutes a multimodal reflex arc, with the Bohm’s bristles providing rapid feedback to set the ipsilateral antennal position whereas the visual system functions in slower context-dependent modulation of positions of both antennae. Integration of these multi-sensory inputs may be critical in ensuring that the antennae are properly positioned during rapid flight maneuvers.