PT  - JOURNAL ARTICLE
AU  - Reichel, Simon V.
AU  - Labisch, Susanna
AU  - Dirks, Jan-Henning
TI  - What goes up must come down Biomechanical impact analysis of jumping locusts
AID  - 10.1101/225672
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 225672
4099  - http://biorxiv.org/content/early/2017/11/27/225672.short
4100  - http://biorxiv.org/content/early/2017/11/27/225672.full
AB  - Many insects are able to precisely control their jumping movements. Previous studies have shown that many falling insects have some degree of control of their landing-orientation, indicating a possible significant biomechanical role of the exoskeleton in air righting mechanisms. Once in the air, the properties of the actual landing site are almost impossible to predict. Falling insects thus have to cope mostly with the situation at impact. What exactly happens at the impact? Do locusts actively ‘prepare for landing’ while falling, or do they just ‘crash’ into the substrate?Detailed impact analyses of free falling Schistocerca gregaria locusts show that most insects typically crashed onto the substrate. There was no notable impact-reducing behaviour (protrusion of legs, etc.). Independent of dropping angle, both warm and cooled locusts mostly fell onto head and thorax first. Our results also show that alive warm locusts fell significantly faster than inactive or dead locusts. This indicates a possible tradeoff between active control vs. reduced speed. Looking at the morphology of the head-thorax connection in locusts, we propose that the anterior margin of the pronotum might function as a ‘toby collar’ structure, reducing the risk of impact damage to the neck joint. Interestingly, at impact alive insects also tended to perform a bending movement of the body.This biomechanical adaptation might reduce the rebound and shorten the time to recover. The adhesive pads also play an important role to reduce the time to recover by anchoring the insect to the substrate.