• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.1
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• pp.15-20
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• 2003

The present investigation was carried out to study the possible cause for reciprocal difference in silkworm hybrids. By utilising the polyvoltine race Pure Mysore (PM) and newly evolved breeds (CSR2, CSR5, CSR16 and CSR17), the direct and reciprocal crosses of polyvoltine ${\times}$ bivoltine and also bivoltine hybrids were studied. The hybrids of polyvoltine ${\times}$ bivoltine (direct) are superior to their reciprocal crosses in respect of cocoon yield, cocoon weight and filament length. The reciprocal crosses of polyvoltine ${\times}$ bivoltine are superior to their direct crosses in respect of fecundity and short larval duration. No significant differences were observed in the characters like cocoon shell ratio, raw silk percentage, denier, reelability and neatness in both polyvoltine ${\times}$ bivoltine direct crosses and their reciprocals. The expression of cocoon characters as a function of sex revealed that direct crosses (polyvoltine ${\times}$ bivoltine) showed higher cocoon weight, pupal weight, shell weight and longer filament length in females than the reciprocal crosses (bivoltine ${\times}$ polyvoltine), where as these characters in males were almost the same in both direct and reciprocal crosses, indicating that the sex-linked genetic factor played a more important role. it was clear that difference in cocoon yield observed in reciprocal crosses of polyvoltine ${\times}$ bivoltine was due to the low cocoon and shell weight in females which was turn due to presence of early maturity genes (Lme) linked with sex-chromosome (X) which effect on larvae period of the silkworm. In bivoltine hybrids, i.e., both direct and their reciprocals crosses, all the characters viz., hatching percentage, larval duration, survival, cocoon weight, cocoon shell weight, cocoon shell ratio, raw silk percentage, filament length, denier, reelability and neatness did not show any significant difference (except number of eggs laid by moth) which could account for presence of same maturity genes (Lm) in both direct and reciprocal crosses. it was clear that reciprocal differences occur when the hybrids are prepared from the parental strains with different voltinism.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.5
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• pp.475-479
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• 1998

Data on body weights were analyzed in the four genetic groups from all possible crosses of two subspecies of mice to estimate average direct genetic effects (ADGE), average maternal genetic effects (AMGE) and heterotic effect (HE). The genetic groups used were $CF_{{\sharp}1}$ laboratory mouse (Mus musculus domesticus), Yonakuni wild mouse (Yk, Mus musculus molossinus yonakuni) and two reciprocal $F_1$ crosses of them, CY and YC. First symbol in the reciprocal $F_1$ represent subspecies of dam. Body weight at 1 (Wk1), 3 (Wk3), 6 (Wk6) and 10 weeks of age (Wk10) were analyzed from 258 mice of the four genetic groups. The model used to evaluate body weights included main effects of genetic group and sex, and interaction effect between genetic group and sex. The ADGE and the AMGE were estimated as deviations of Yk from $CF_{{\sharp}1}$. The HE was estimated from the differences between the reciprocal $F_1$ and the midparent mean. Results of this study showed that all effects, except sex and interaction between genetic group and sex at Wk1 and Wk3, were highly significant source variation (p < 0.01). The ADGE were positive and highly significant (p < 0.01) at all ages studied for both sexes, while the AMGE were highly significant at Wk3, Wk6 and Wk10. The ADGE were larger in contributing effect on body weight differences than the AMGE. The positive value of the HE were observed at all ages for males, while for females the positive effects occured from birth through weaning.