Effect of surface roughness on attachment ability of locust Locusta migratoria manilensis

• Studied friction force of locust on substrates with variable surface roughness.
• Friction forces show variations of inverted parabola, linear pattern and saturation.
• Surface roughness with critical values extremely reduces locust attachment ability.
• Mechanical analysis of the interaction between claw tip and surface irregularity.

To explore how surface roughness affects locust׳s attachment ability, friction force of locust Locusta migratoria manilensis on substrates with variable roughness was measured with an insect micro-force measurement system. Extensive values of the friction force were acquired, respectively exhibiting the trends of inverted parabola variation, linear pattern growth and saturation period with the increased surface roughness. Obviously small values of the friction force were generated by locusts on substrates possessing a particular roughness range. The morphology and structure of locust attachment organ were examined and quantitively analyzed with a scanning electron microscope. Based on the acquired structure information, a schematic was proposed to explain the interaction between the attachment organ and the surface irregularity, also a mechanical analysis was conducted to present the effect of surface asperity on locust׳s claw tip. Results demonstrated that surface roughness with appropriate values can considerably reduce locust׳s attachment ability via simultaneously restricting the generation of mechanical interlock and adhesive attachment. The achieved conclusion gives a further interpretation to friction behavior of insect on variable substrates, also provides theory for biomimetic designing a slippery plate utilized for trapping plague locusts.