Effect of vitamins on the growth and development of the mulberry silkworm, Bombyx mori L.

Abstract

The effect of the supplementation of mulberry leaves with vitamin B2 and C at different concentrations (e.g. 60, 150, 240, 330 and 420ppm for vitamin B2 and 10000, 15000, 20000, 25000 and 30000ppm for vitamin C) throughout different seasons, e.g. S-1, S-2, S-3 and S-4, at different feeding schedules, e.g. fed every day in 1st feeding of 3rd to 5th instar larvae (FS-1), fed in 1st to 5th feeding of 3rd to 5th instar larvae (FS-2), fed only in 1st feeding of 3rd to 5th instar larvae (FS-3) on the growth and development of B. mori were assessed in this investigation. The supplementation of vitamin B2 increased the WML, LML and BML under different concentrations (except 420ppm) compared to the control while fed according to FS-1, FS-2 and FS-3 in S-1. The highest and the lowest results of these parameters were observed at 240ppm and 420ppm respectively. Similar results were also found in S-2, S-3 and S-4. At FS-1, FS-2 and FS-3 while the supplementation of vitamin B2 slightly increased the PW under different concentration, e.g. at 60ppm, 150ppm, 240ppm and 330ppm in comparison to the control in S-1, S-2, S-3 and S-4. Vitamin B2 significantly increased the CW, CL, CB, SW, SP, TEL and EHP of B. mori at different feeding schedules under different seasons. Generally, the highest and the lowest results for these parameters were recorded at 240ppm and 420ppm respectively. In case of SR% the most effective concentration of vitamin B2 was not followed the normal trend as found in other parameters. On the other hand, vitamin B2 slightly decreased the larval period, pupal period and mortality percent at different concentrations except 420ppm compared to the control. The results of physiological parameters like food consumption, food utilization, food digestibility, food consumption index and co-efficient of food utilization were significantly increased in different concentrations (e.g. 60ppm, 150ppm, 240ppm and 330ppm.) under different feeding schedules and seasons. The results of ANOVA indicated that the items of feeding schedules, seasons and doses showed highly significant differences for all the parameters at 1% level of significance. But the item dose × season showed insignificant results in majority of the cases. The effectiveness of vitamin B2 with respect to different seasons on different characters under study followed the order S-2 > S-1 > S-3 > S-4, while in respect of different feeding schedules this trend has been in the order of FS-2 > FS-3 > FS-1. The most effective dose of vitamin B2 followed the order 240ppm > 150ppm > 60ppm > 330ppm. In case of vitamin C supplementation, WML, LML and BML were increased at different concentrations except 30000ppm compared to the control while fed in FS-1, FS-2 and FS-3 during different seasons. The mean values of PW were also increased at different concentrations, e.g. at 10000ppm, 15000ppm, 20000ppm and 25000ppm in comparison to the control. Similar results were also recorded for CW, CL, CB, SW, AE%, TEL and EHP of B. mori at different feeding schedules and seasons. In these cases the highest and lowest results were observed at 15000ppm and 30000ppm respectively. Vitamin C supplementation reduced the developmental periods in B. mori at majority concentrations except 30000ppm. It was also found that the mortality percent of B. mori was significantly decreased in these concentrations. The physiological traits like FC, FU, AD%, FCI and CFU of B. mori were enhanced against all the concentrations except 30000ppm compared to the control. In most of the cases the result of ANOVA indicated that the items of feeding schedules, seasons and doses showed highly significant differences at 1% level of significance. In majority of the cases it was observed that the effective dose of vitamin C on different characters followed in the order of 15000ppm>20000ppm>10000ppm> 25000ppm and in respect of feeding schedules it was in the order of FS-2> FS-1>FS-3. The most effective season was found in the following order S-2> S-1> S-3> S-4. Finally, the results depicted that the supplementation of vitamin B2 and C at some concentrations e.g. 60ppm, 150ppm, 240ppm, 330ppm of B2 and 10000ppm, 15000ppm, 20000ppm, 25000ppm of vitamin C may have beneficial effects on the physiological parameters, larval growth, cocoon characters and survival percentage by stimulating metabolic processes of the silkworm B. mori. Although it was observed that the growth and development of B. mori took place upto a particular dose 240ppm of vitamin B2 and 15000ppm of vitamin C at FS-2. So, this supplementation could be prescribed to the farmers to get more quantity of silk. On the contrary, higher concentrations, e.g. 420ppm of B2 and 30000ppm of C reduced the growth parameters and increased the developmental period and mortality percent. It may be due to hypervitaminosis.