SEASONAL-VARIATIONS IN THE SILK YIELD CONTRIBUTING CHARACTERS OF 42 STRAINS OF THE SILKWORM, BOMBYX-MORI (LEPIDOPTERA, BOMBYCIDAE)

Forty-two strains of the silkworm, Bombyx mori (L.), collected from Ch ina, Japan, Vietnam, South Korea, Brazil, India, and France were reare d in the spring, summer and autumn seasons during 1991-92 at the Regio nal Station of Central Sericultural Research and Training Institute, C oonoor, Tamilnadu State, India. Analyses were made on five silk yield- contributing characters, namely pupation rate, cocoon weight, shell we ight, cocoon shell ratio, and silk filament length. Results indicated the superiority of the following strains for all the above mentioned c haracters: 14M and JC2P !in spring); NBJBO and JC2P (in summer); and M 2, NBJPO and SPJ2 (in autumn). The importance of rearing a given strai n of silkworm in the optimal season for its maximum economic value in terms of silk yield is discussed.