Abstract
Eleven inbred silkworm lines (M-101, M-103, M-104, M-107, Pak-1, Pak-3, Pak-2, Pak-4, PFI-1, PFI-2, and S-1) were evaluated for various parameters of cocoon production under different temperature and relative humidity conditions (25±1,30±1, and35±1 °Cin combination with 55, 65, and 75% RH for three hrs during 4th and 5th instar. The experiment was laid out in factorial design with three replications. Significant variations in the performance of silkworm lines were noticed due to influence of temperature and RH treatment on 4th and 5th instar larvae. The silkworm lines performed significantly better when the larvae were reared at25±1 °Cwith 70–80% RH while almost all the silkworm lines showed poor performance at higher temperature exposures for 3 hrs. Exposures to lower humidity (55%) during larval rearing in 4th and 5th instar at different temperatures (25±1,30±1, and35±1 °C) resulted in lowering the cocoon production. The cumulative evaluation index values for different traits showed that Pak-4 (61.42) was the best line followed by M-101 (59.15), Pak-2 (56.37), Pak-3 (52.83) PFI-I (52.62), and M-107(50.03). The study clearly underlines the importance of optimization of environmental conditions during larval rearing in relation to commercial cocoon production. The investigations strongly recommend that temperature and relative humidity in the range of 25-26 °Cand 70–80%, respectively, are mandatory for excellent results of cocoon production and Pak-4, M-101, Pak-2, Pak-3, PFI-I, and M-107 were suitable for commercial rearing.
Highlights
Silkworm is one of the most important animals which produces silk thread in the form of cocoon by consuming mulberry leaves during larval period
The performance of inbred silkworm lines was evaluated by Evaluation index value (EI) for silkworm breed performance was calculated by following Mano et al [16]
Conditions of temperature and humidity has been presented in Figure 3 that showed lower cocoon weight by almost all silkworm lines
Summary
Silkworm is one of the most important animals which produces silk thread in the form of cocoon by consuming mulberry leaves during larval period. The biological as well as cocoonrelated characters are influenced by ambient temperature, rearing seasons, and genetic constitution of silkworm strains [2]. Rearing conditions affects growth and development of larvae and cocoon production [6]. Some strains of silkworm due to consistent domestication have become highly sensitive to variations in environmental conditions, especially seasonal variations in temperature and humidity in tropical parts of the subcontinent [5, 10]. Environmental stress during silkworm rearing adversely affects growth and development and impairs the production of good quality silk seed with resistance to diseases and ability to withstand high temperature and humidity [11]. The present study, was conducted to find out the effect of variations in temperature and humidity during rearing on silk worm egg production and egg fertility of the silkworm, B. mori. The study would be helpful in popularizing sericulture in farming community
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