Composition and Function of Spider Glues Maintained During the Evolution of Cobwebs

Area of Science:

• Biomaterials science
• Arachnology
• Adhesive chemistry

Background:

• Spiders use capture silks as biological glues to ensnare prey.
• Orb web spider silk contains hygroscopic salts and glycoproteins for adhesion.
• Cobweb spider adhesives in gumfoot threads differ from orb web silk, with unknown compositions.

Purpose of the Study:

• To investigate the composition and adhesive properties of cobweb spider gumfoot silk.
• To compare the adhesives of cobweb spiders (Latrodectus hesperus) with those of orb web spiders.
• To identify components responsible for adhesion in dry to humid conditions.

Main Methods:

• Spectroscopic analysis of gumfoot silk.
• Staining techniques to identify silk components.
• Adhesion studies under varying humidity levels.

Main Results:

• Latrodectus hesperus gumfoot silk contains hygroscopic organic salts and water-insoluble glycoproteins.
• Organic salts are crucial for adhesion, functioning at lower humidity than previously observed.
• Cobweb and orb web spider silks exhibit greater similarities in viscid silk composition than expected.

Conclusions:

• Spider gumfoot adhesives share key components with orb web viscid silks.
• Hygroscopic salts play a significant role in modulating adhesion across different humidity levels.
• Findings offer insights for developing synthetic adhesives for diverse environmental conditions.