Genomic adaptation to polyphagy and insecticides in a major East Asian noctuid pest

The tobacco cutworm, Spodoptera litura, is among the most widespread and destructive agricultural pests, feeding on over 100 crops throughout tropical and subtropical Asia. By genome sequencing, physical mapping and transcriptome analysis, we found that the gene families encoding receptors for bitter or toxic substances and detoxification enzymes, such as cytochrome P450, carboxylesterase and glutathione-S-transferase, were massively expanded in this polyphagous species, enabling its extraordinary ability to detect and detoxify many plant secondary compounds. Larval exposure to insecticidal toxins induced expression of detoxification genes, and knockdown of representative genes using short interfering RNA (siRNA) reduced larval survival, consistent with their contribution to the insect's natural pesticide tolerance. A population genetics study indicated that this species expanded throughout southeast Asia by migrating along a South India-South China-Japan axis, adapting to wide-ranging ecological conditions with diverse host plants and insecticides, surviving and adapting with the aid of its expanded detoxification systems. The findings of this study will enable the development of new pest management strategies for the control of major agricultural pests such as S.litura

Developmental Aspects of Mulberry and Nonmulberry Silkworm Species: A Comparative Study

The mulberry silkworm, Bombyx mori has been exploited by man for more than 4000 years, for the production of the exotic silk yam used in making fabric. The silk fibre, proteinaceous in nature synthesised by B. mori larvae, is unmatched in beauty and elegance by any of the man made fibres. The silk industry is reported to have its origin in China dating back to 2600 B.C. and found its way to India over the Himalayas. According to the recorded history, a young Chinese Empress by name Si Ling-Chi has been accredited with the development and exploitation of the silk cocoon for the production of exotic silk fibre. The silk industry spread widely in Europe in the sixth and seventh centuries A.D