Meeting Abstract
The physical properties of a substrate affect locomotor performance. Here, we examine how locust jump velocity is affected by the stiffness (spring constant) and effective mass of the substrate by using bending beams of variable width and thickness. We used nymphal locusts (0.8 +/- 0.2 grams), which use a catapult mechanism for propulsion. Locusts jumping from substrates with a lower spring constant achieved significantly smaller take-off velocities than jumps from stiffer substrates (F1,98=5.29, p = 0.024; velocity = 0.8 +/- 0.19 m/s on substrate of k=2.51 m/N vs. velocity = 0.73 +/- 0.17 m/s on substrate of k=0.94 m/N). Jumps from substrates with the same compliance but a larger effective mass (corresponding to 1.86 times the locusts’ average body mass) resulted in significantly higher take-off velocities than jumps from lighter substrates (corresponding to 0.46 times the locusts’ average body mass)(F1,164 = 9.47; p =0.0025; velocity = 0.88 +/- 0.18 m/s on heavy substrates, velocity = 0.79 +/- 0.19 m/s on light substrates). The difference in take-off velocity between heavy and light substrates was larger for smaller insects (F1,164 = 0.64; p = 0.038). This result suggests that both the inertia and the compliance of the substrate play an important role in the resulting performance.
