Meeting Abstract
P1.95 Sunday, Jan. 4 Sudden shadow triggers a short-latency behavioral response in flying praying mantises GASSER, B.A.; PANESSITI, M.*; YAGER, D.D.; Univ. of Maryland, College Park ddyager@umd.edu
An abrupt decrease in light intensity from a small overhead source elicits a complex behavior in flying praying mantises both in tethered flight and in free-flight. In Pseudocreobotra ocellata, the response comprises a complete extension of the prothoracic legs, changes in wing beat pattern, dorsal abdominal muscle contraction, and sometimes a head roll. In addition, the mesothoracic and metathoracic legs move slightly away from their normal tucked position. An abrupt increase in light intensity (flash or sustained) did not trigger any behavior. The latency to the beginning of the prothoracic leg movement is 40-60 ms and the wing beat changes start within two cycles (60-80 ms). Wing beat rate, phase, and amplitude changes were obvious in laser/photocell and EMG records, but were markedly inconsistent in magnitude. Shadow never caused flight cessation, and it triggered flight in non-flying animals hanging without tarsal contact. Lowering the contrast between full light and shadow reduced the response magnitude. Three additional mantis species also responded strongly to sudden shadow. Although closely resembling the ultrasound-triggered evasive response, there are differences between the behaviors, most obviously in the prothoracic leg extension. High-speed video shows that for ultrasound, the sequence of extension of the three leg joints is proximal to distal, but it is distal to proximal for shadow stimuli. Also, the response to ultrasound greatly outlasts the stimulus, but stimulus and response durations are the same for shadows. P. ocellata and Hierodula grandis flying untethered in a large room responded to lights-off with an abrupt dive followed by acceleration upward. Direction change ranged from 0 to 180 to either side. Suddenly increased light intensity had no effect. We suggest that sudden shadow and ultrasonic stimuli during flight may tap into the same CNS module for defensive behavior.
