Evaluation of physico chemical characteristics of silk fibres of Antheraea assama reared on different host plants

The golden-yellow silk fibres obtained from Antheraea assama Westwood (Lepidoptera: Saturniidae) reared on leaves of three different host plants belonging to the family Lauraceae, were studied to evaluate their characteristic physico-chemical properties. The host plants, Machilus bombycina king, Litsaea polyantha A. Juss and Litsaea citrata Roxby, significantly influenced silk length, width, sericin and amino-acid contents of the fibres. The contents of the predominant amino-acids; glycine (10.55 μg), aspartic (5.43 μg) and serine (7.15 μg), were higher in fibres obtained from cocoons of A. assama fed on M. bombycina, while alanine (9.46 μg) was higher in the fibres of cocoons obtained from the other two host plants. The breaking load (17.791 g) and tenacity (3.562 g/d) were higher in cocoons from the host plant M. bombycina. The X-ray diffraction patterns showed the amorphous nature of the fibres obtained from the cocoons of A. assama fed on L. polyantha and L. citrata, while fibres obtained from cocoons from M. bombycina showed amorphous bands with little tendency to two dimensional order. Above all, the natural golden yellow hue of the fibre, which is one of the most important and commercially valuable added properties of this particular silk variety, was better retained in the fibres extracted from cocoons of A. assama larvae reared on M. bombycina.