Hatchability and Survival of silkworm Bombyx mori and Eri Worms under Controlled Environmental Conditions in Uasin Gishu County

Abstract

Eri worm (Samia Cynthia racini), a domesticated non-mulberry silkworm is polyphagous and multivoltine, while mulberry silkworm (Bombyx mori) is bivoltine and feeds on mulberry leaves. Domesticated silkworms are highly sensitive to environmental fluctuations, making the adaptability to environmental conditions different from wild silkworm. In Uasin Gishu temperatures range between 8.40C and 270C which are not suitable for the hatching and rearing of silkworm. The experimental treatments were done in pre-constructed structures with the dimensions of equal dimensions (4mx4m and 3m height). Iron roofing with enclosed concrete walls (L0), iron roofing with enclosed timber walls (L1), iron roofing with mud walls (L2) and greenhouses with flaps designated L3 (green house with all flaps open,) 3 flaps open (L4), 2 flaps open (L5), 1 flap open (L6) and one completely enclosed (L7) were used to test hatchability, survival and durations. The green house flaps were fitted with a net gauze to protect entry of predators. The control condition was in a thermo scientific incubator (L8) at the laboratory, with 3 replicas under constant temperature and humidity. The temperature and relative humidity were recorded using hygrometer/thermometer, while the duration to every instar and survival was recorded. The mean room temperature ranged between 30.310C±1.7 in L6 to 23.850C±1.86 in L0, and mean relative humidity of 75%±0.00 (L7) and 29.93%±3.85 (L4) was statistically significant. The time to hatching was 3 days (L0) to 6 days (L1, L2). Percent hatching was 88.8% and 91.83% for B. mori and Eri respectively in L1 but lowest in L4. Larval duration (34 days) was longest for B. mori and 26 days for Eri. Larval survival percentage was highest in L2 (76.73±4.81) for B. mori and 77.40±3.67 for Eri (L0). Greenhouse with all flaps open and mud walled structure could provide suitable conditions for sericulture production in Uasin Gishu County.