Arousal from Tonic Immobility by Vibration Stimulus
Tonic immobility (TI) is an effective anti-predator strategy. However, long immobility status on the ground increases the risk of being eaten by predators, and thus insects must rouse themselves when appropriate stimulation is provided. Here, the strength of vibration causing arousal from the state of TI was examined in strains artificially selected for longer duration of TI (L-strains: long sleeper) in a beetle. We provided different strengths of vibration stimuli to the long sleepers in Tribolium castaneum. Although immobilized beetles were never awakened by the stimuli from 0.01 to 0.12 mm in amplitude, almost of the beetles were aroused from immobilized status by the stimulus at 0.21 mm. There was a difference in sensitivity of individuals when the stimuli of 0.14 mm and 0.18 mm were provided. F2 individuals were also bred by crossing experiments of the strains selected for shorter and longer duration of TI. The arousal sensitivity to vibration was well separated in the F2 individuals. A positive relationship was observed between the duration of TI and the vibration amplitude, suggesting that immobilized beetles are difficult to arouse from a deep sleep, while light sleepers are easily aroused by even small vibrations. The results indicate a genetic basis for sensitivity to arousal from TI.
KeywordsBeetle Crossing experiment Death feigning Selection experiment Thanatosis Tribolium
We thank Mrs. N Hayashi for assistance of the experiment. This work was supported by a Grant from Grant-in-Aid for Scientific Research, KAKENHI 17H05976 and 18H02510, MEXT, JSPS to T.M.
T.M. designed the study. K.M., R.K., K.O., J.Y. T.M. collected data. T.M., KM analysed the data. TM, RF, NN interpreted the results and wrote the manuscript. All authors gave final approval for publication.
Compliance with ethical standards
Conflict of interest
Takahisa Miyatake, Kentarou Matsumura, Ryota Kitayama, Keiichi Otsuki, Ji Yuhao, Ryusuke Fujisawa and Naohisa Nagaya declare that they have no conflict of interest.
This study was not required to complete an ethical assessment prior to conducting our research.
Human and animal rights and informed consent
This article does not contain any studies with human participants or animals performed by any of the authors.
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