Propriedades físicas de sedas de lepidópteros neotropicais

Abstract

Silk fibers produced by non-domesticated moths have distinct properties from the widely cultivated Bombyx mori silk and show promising applications in several areas. However, few Lepidoptera species have their silk adequately characterized, the studies so far concentrating on a few groups of wild silk moths. For the Lepidoptera group, in addition to the construction of cocoons, the silk is used to construct collective shelters, migration, lifelines, and, in rare cases, to capture prey. Therefore, understanding the composition and properties of these silks can help understand their role in the biology of these species and their possible applications. In this work, tensile tests and ATR-FTIR analysis of silks from seven species were performed, and the results were analyzed by multilinear regression, Principal Component Analysis (PCA), and Cluster Analysis. Silk fibers from wild moths have a wider cross-section than butterfly silks, probably due to the energy savings needed to survive these species with gregarious or nomadic habits. According to our results and data from the literature, the average Young's moduli for silks from Papilionoidea, Psychidae, Saturniidae, and Sphingidae are 3.5, 21.4, 5.4, and 5.9 GPa, respectively. Furthermore, the silk from Papilionoidea has lower tensile strength than other Lepidoptera. Our results support the correlation between the silk's mechanical properties and ß-sheet polyalanine, ß-sheet polyalanine-glycine, serine, and oxalate concentrations (inferred from the corresponding infrared absorption band's intensity) for the Nymphalidae, Papilionidae, Psychidae, Saturniidae, and Sphingidae families. [resumo fornecido pelo autor]