The ladybird beetle (Coccinella septempunctata) is known for swift deployment of its elytra, an action that requires considerable power. However, actuation by thoracic muscles alone may be insufficient to deploy elytra at high speed because the maximum mechanical power that elytral muscles can produce is only 70% of that required for initiation of deployment. Nevertheless, the elytra open rapidly, within 3 ms in the initial phase, at a maximum angular velocity of 66.49±21.29 rad s−1, rivaling the strike velocity of antlion (Myrmeleon crudelis) mandibles (65±21 rad s−1). Here we hypothesize that elytra coupling may function as an energy storage mechanism that facilitates rapid opening by releasing elastic strain energy upon deployment. To test this hypothesis and better understand the biomechanics of elytra deployment, we combined micro-computed tomography and scanning electron microscopy to examine the microstructure of the coupling of paired elytra. We found that two rows of setae on the internal edges of the elytra coupling structure undergo elastic deformation when the elytra are locked together. Kinematics observations and mathematical modelling suggest that the elastic potential energy stored in the compressed setae generates 40% of the power required for deployment of elytra. Our findings broaden insights into how ladybirds actuate elytra opening by a strategy of using both muscles and elastic microstructures, and demonstrate a distributed pattern of actuation that adapts to geometrical constraints in elytra locking.
Inside the coupling of ladybird beetle elytra: elastic setae can facilitate swift deployment
These authors contributed equally to this study.
- Award Group:
- Funder(s): National Natural Science Foundation of China
- Award Id(s): 51905556
- Funder(s):
- Award Group:
- Funder(s): Science and Technology Planning Project of Guangdong Province
- Award Id(s): 2020A1414040007
- Funder(s):
- Award Group:
- Funder(s): Sun Yat-sen University
- Award Id(s): 76200-18841223
- Funder(s):
- Award Group:
- Funder(s): Shenzhen Science and Technology Innovation Program
- Award Id(s): GXWD20201231165807008
- Funder(s):
Currently Viewing Accepted Manuscript - Newer Version Available
Qiufeng Yuan, Le Zong, Jie Zhang, Jianing Wu, Yunqiang Yang, Siqin Ge; Inside the coupling of ladybird beetle elytra: elastic setae can facilitate swift deployment. J Exp Biol 2022; jeb.244343. doi: https://doi.org/10.1242/jeb.244343
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