Structure, Composition, and Properties of Silk from the African Wild Silkmoth, Anaphe panda (Boisduval) (Lepidoptera: Thaumetopoeidae)

Abstract

Silk cocoon nests, as well as the fiber structure, compositions, and properties of the African wild silkmoth, Anaphe panda, collected from Kakamega tropical rainforest (western Kenya) were studied using scanning electron microscopy, high-pressureliquid chromatography, tensile tests, and thermogravmetric analysis, and they were compared with the industrial standard, Bombyx mori. Cocoon nests are complex structures made up of inner, middle, and outer layers. The inner hard parchment was found to protect a mass of (20–200) individual soft flossy cocoons that enclose the pupae. The outer surface of the cocoon nests was covered with a mass of hair-like bristles. Fibers contained crescent-shaped and globular cross-sections with nods at regular intervals. Alanine (34%) and glycine (28%) were the dominant fibroin amino acids observed. Total weight loss after degumming the cocoon nest was 25.6%. Degummed fibers showed higher moisture regain of 9% when compared with cocoon nests (8%). The fibers had 0.4 GPa breaking stress and 15.4% breaking strain. Total weight loss values after thermogravimetric analysis were 86% and 90% for degummed fibers and cocoon shells, respectively.