Performance of Bombyx mori and Samia cynthia ricini silkworms under controlled environmental conditions in Uasin Gishu County

Abstract

The domesticated silkworm Bombyx mori and Eri worm (Samia cynthia ricini) are bivoltine and multivoltine, feeding exclusively on mulberry and castor leaves, respectively. The domestication of silkworms has made them highly sensitive to fluctuations in temperature and relative humidity. The research determined the performance of silkworm reared inside pre-constructed structures with equal dimensions (4 m x 4 m x 3 m height), with iron roof; timber walled (L1) and mud walled (L2). Greenhouses with four flaps open (L3), three sides open (L4), two sides open (L5), one side open (L6) and completely enclosed (L7), and concrete walled (L0) were used. The survival percentage, larval duration and cocoon quality and quantity were tested and compared. The temperature and relative humidity were recorded. The mean temperature of structures during rearing ranged between 22.73 °C±1.86 (L0) and 31.63 °C±0.81 (L7) during the wet season with a similar trend in the dry season, the mean relative humidity of 33.26%±7.29 (L1) and 43.18%±9.53 (L0) during the wet season and 33.11%±7.27 (L1) and 42.16%±7.38 (L7). Larval duration was longest in L2 for both B. mori and Eri during the wet season. Larval survival was highest in L2 (76.73±4.20%) and L0 (78.70%) during the wet and dry season respectively. A similar trend obtained in L2 (77.00%) and L0 (80.10%) for Eri in wet and dry season respectively. The cocoon weight was highest in structure L2 (0.86±0.03) during the dry season, L5 (2.78±4.30) during the wet season. Eri cocoon weight was highest in L0 (2.35±0.49) during the wet season and highest in L3 (2.44±0.34) in the dry season. The longest significantly different Filament length for B. mori was in L2 (1377.80±150.17 m). During the dry season L3 (1382.80±117.23m) was the longest. For the Eri the longest filament length was from L2 (437.6±32.26). The seasons did not influence average survival, filament length and weights from the tested structures.