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Embryonic diapause is the suspended animation responsible for the onset of Voltinism in the silkworm. The embryo is completely arrested during the developmental event to overcome unfavourable environmental conditions. This further results in the synthesis of sorbitol from glucose and examines the differences between sorbitol levels in the diapause-induced silkworm eggs of APM1, MU303 and PM strains by exposure to photoperiodic regime of 16L:08D, 14L:10D and 12L:12D. The results obtained revealed the fact that the sorbitol level is high during the 6th day in all the selected strains at their 7th and 8th generation. This indicates that the enhancement of the sorbitol is independent of the induced diapause in all three strains of the mulberry silkworm. Further, it is also clear that the enhancement of sorbitol concentration is devoid of a photoperiodic regime.

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In the present investigation an attempt has been made to study the various parameters of consumption indices in relation to the different concentration of cholesterol supplementation during 4 th instar silkworm of FC1XFC2 and FC4XFC3 hybrids. The food consumption comprises the ingesta and digesta during 4 th instar showed the level of ingesta was significantly higher compare to digesta in all the cholesterol treated batches in all 4 days, but on 4 th day the rate of food consumption represents the highest rate of ingesta in the selected hybrids. Similarly the approximate digestibility was maintained ranging from 50-85% in cholesterol treated batches, whereas the efficiency of conversion of food ingested and efficiency of conversion of food digested were low ranging from 5-38% in FC1XFC2 and FC4XFC3 silkworm hybrids. The consumption index and coefficient of metabolism are the two nutritional parameters indicates the maximum attainment ranging from 0.8-0.9 ratio in all the days in all the cholesterol treatment concentration, whereas the growth rate was constantly maintained during 4 th instar ranging from 0-0.05 throughout the instar in FC1XFC2 and FC4XFC3 hybrids. The pattern of changes in the ingesta and digesta of 5 th instar silkworm, but cholesterol supplemented during 4 th instar extended the above parameters ranging from 9-14g from first day to day seventh, whereas the digesta falls within a range of 9g during 5 th instar in both the hybrids. The efficiency of conversion of food ingested, efficiency of conversion of food digested and approximate digestibility of 5 th instar silkworm hybrids treated with three doses of cholesterol during 4 th instar a showed the magnitude of changes above the level of 50% in FC4XFC3 hybrid, but the FC1XFC2 represents less than level of 50% except 5 th day and 7 th day during 5 th instar. The consumption index, growth rate and co-efficient of metabolism were calculated during 5 th instar the ratio was ranging from 0-1 in all the three parameters except consumption index and coefficient of metabolism on 7 th day ranging from 6-7 and 2-3 on respectively on the last day of 5 th instar in FC1XFC2 and FC4XFC3 hybrids.

The effect of different concentration of cholesterol treatment during 4 th instar and economic characters were better manifested in larval weight except larval duration and significant improvement in cocoon characters and egg characters were observed in FC1XFC2 hybrid. Similarly, FC4XFC3 hybrid has been subjected for the cholesterol treatment during 4 th instar showed an unchanged larval duration in control and treated silkworms and enhancement in larval weight, cocoon characters and filament characters were highly significant except denier and renditta at 0.01 M concentration showed a negative relationship with reference to cholesterol supplementation. The egg characters of FC4XFC3 hybrid responded relatively better in the performance of egg hatching and fecundity. The impact of supplementation of cholesterol during 5 th instar silkworm hybrid namely, FC1XFC2 contributed to the improvement of all the economic parameters comprising larval characters, cocoon characters, filament characters and egg characters except unchanged larval duration in control and untreated batches. On the other hand, FC4XFC3 hybrid were subjected for the application of different concentration of cholesterol treatment during 5 th instar and expression and manifestation of the larval characters and cocoon characters were responded significantly except larval duration and cocoon weight at 0.1 M concentration showed relatively low in the cocoon weight compare to control batches. The filament length and weight of FC4XFC3 hybrid showed a consistent increase in the improvement of the traits, whereas the denier and renditta were inversely related to control and negatively correlated but at 0.1M concentration showed positive trend with respect to Renditta as observed in the investigation. The egg characters namely, fecundity and egg hatching in relation to the cholesterol administration and its impact leads to the enhancement in the rate of traits of selected bivoltine.