Robust Performance of Spider Viscid Silk on Hairy and Smooth Insect Substrates

Area of Science:

• Biomaterials science
• Entomology
• Adhesion science

Background:

• Spider viscid silk acts as a smart-adhesive, adjusting properties like viscosity and adhesiveness based on ambient humidity.
• Spiders optimize silk water uptake for their environment, achieving a universal viscosity balancing spreading and cohesive energy for adhesion.
• Current adhesion models for spider silk are primarily based on experiments with smooth surfaces.

Purpose of the Study:

• To test if less viscous,
• over-lubricated
• spider silk exhibits increased adhesion on rough, hairy insect surfaces compared to smooth surfaces.
• To investigate the effect of surface topography (hairy vs. non-hairy) on the adhesive performance of spider silk under varying humidity levels.

Main Methods:

• Adhesion tests were conducted using the viscid silk of the furrow spider (Larinioides cornutus).
• The silk's adhesion was tested on honey bee (Apis mellifera) thoraxes, both with and without natural hairs.
• Tests were performed under two humidity conditions: high and medium.

Main Results:

• The
• over-lubricated
• spider silk demonstrated increased adhesion on hairy insect surfaces.
• The adhesive performance of the less viscous silk on hairy surfaces was comparable to that of an optimally viscous silk.
• Humidity levels influenced the silk's adhesive properties, as expected for a humidity-sensitive adhesive.

Conclusions:

• Spider silk's adhesive strategy is more complex than previously understood, with surface topography playing a crucial role.
• The ability of spider silk to adhere effectively to diverse surfaces, including hairy insects, is enhanced by its tunable viscosity.
• Findings suggest that spider silk's "smart-adhesive" properties are critical for prey capture in complex natural environments.