Flight muscle coordination and body orientation changes ofLocusta migratoriaduring collision avoidance behaviour

Abstract

AbstractAnimals display a variety of adaptive behaviours responsible for collision avoidance and escape from predators. Complex neural control mechanisms underly these behaviours, which are controlled by specialized neural circuits.Locusta migratoriais a tractable organism for examining flight muscle coordination of collision avoidance behaviour. Loose tether experiments have shown that locusts free to manoeuvre in 3-dimensional space will adjust wing beat frequency, coordinate timing of a single bilateral pair of flight muscles, and coordinate forewing asymmetry during the downstroke. Current experiments were designed to test two hypotheses: 1) Synchrony between flight steering muscles increases prior to initiation of intentional flight steering behaviour. We analyzed EMG recordings from bilaterally paired forewing m97 (1stbasalar), m99 (subalar), and hindwing m127 (1stbasalar) steering muscles. 2) Timing and synchrony of flight muscle activity correlate with body orientation changes during intentional flight steering. Concurrent electromyographic (EMG) and high-speed video allowed for simultaneous measurements of muscle activity and body orientation changes. We found that during turns, ipsilateral synchronization between fore (Lm97) and hind (Lm127) occurred, followed by bilateral synchrony between left and right forewing flight muscles Lm97 and Rm97. These synchrony events correlate strongly with onset of turns and body orientation changes within the pitch and roll rotational planes. These findings demonstrate the earliest detectable muscle activity event that predicts the initialisation of turning during collision avoidance behaviour.Summary statementSynchronization of locust forewing flight muscles strongly correlates with body rotation during flight steering evoked by objects approaching on a collision course.