Silk properties of Asian weaver ant changes over time: an understanding of nest protection from natural calamities

Abstract

Insect silk is a naturally occurring protein that forms semicrystalline threads when exposed to air. The Asian weaver ant, Oecophylla smaragdina (Formicidae: Hymenoptera), frequently uses silks for leaf weaving in nest construction to maintain its integrity and durability. The silk imparts resilience and durability to the nests, preventing fracturing or breaking during many natural disasters, particularly heavy rainfall and strong winds. Therefore, understanding the strength and stability of these silk threads necessitates an examination of their structural components and physicochemical properties. Silk samples aged 30 days, 180 days, and 365 days are analysed to assess the temporal differences in silk durability and hardness. According to infrared Fourier transform studies, the silk mostly consists of alkanes, alkenes, amides, and alcohols, while energy-dispersive X-ray analysis identifies carbon, nitrogen, and oxygen as the principal elements, with minor quantities of magnesium, aluminium, silicon, and potassium. As per X-ray powder diffraction, the silk exhibits a crystalline sheet structure. Its mass, thickness, density, and tensile strength increase as the silk becomes older. The ‘contact angle’ of the silk also increases with age, indicating its hydrophobic nature. The thermogravimetric curve shows the fibre’s long-term endurance and thermal stability. The physicochemical properties of Oecophylla silk highlight its unique strength and endurance, explaining why they utilise its advantages to protect their nests from severe environmental conditions.