Effects of Gravidity on Maximal Jump Performance in the American Locust (Schistocerca americana)

Effects of Gravidity on Maximal Jump Performance in the American Locust (Schistocerca americana)

Biology

Truini, Dana

Rosemary Patterson
Guillermina Seri

6/11/2023

The negative effects of gravidity on locomotion have been well documented in terrestrial vertebrates but are relatively unknown in insects. The gravid phase of Schistocerca americana lasts only four days, and during this time period, females can gain up to an additional 40% of their metabolic body mass. Larger grasshoppers have significantly more eggs, a larger egg mass, and a greater portion of their body dedicated to eggs. We investigated how jump biomechanics varied between nongravid and gravid grasshoppers. We used Qualisys infrared high-speed cameras (at 1121 fps) to track the locomotion of 19 sexually mature female grasshoppers of various gravidities. We then calculated the biomechanics of locomotion using the data processor Qualisys Track Manager (QTM) and analyzed one maximal jump from each grasshopper. We investigated factors such as take-off velocity, horizontal take-off velocity, vertical take-off velocity, take-off angle, jump distance, jump height, time spent in air, and rotations in the air. We found that more gravid grasshoppers have significantly shorter jump distances. We also found that these larger grasshoppers have a significantly slower take-off velocity. There was no significant difference in either vertical or horizontal take-off velocities. Gravid grasshoppers also produce less jump energy per gram muscle. There was no significant difference in take-off angle, jump height, time spent in air, center of mass, or rotations during jumps. Since the jumping muscles are the same size in gravid and nongravid grasshoppers and performance is decreasing, the muscles are not compensating for the additional mass. Additionally, egg mass compresses tracheal oxygen delivery, and therefore, gravid grasshoppers may potentially rely more on anaerobic metabolism (arginine phosphate and LDH) for jumping. Future work will investigate how ATP production varies.

thesis

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