Effect of young and mature coconut water on cocoon characters of Thai polyvoltine strains, Nang-Noi and Nang-Lai, of the silkworm, Bombyx mori

Supplementation with young and mature coconut water was carried out at day 2 and at day 4, the fifth instar, total two times or four times, to two Thai polyvoltine strains, Nang-Noi and Nang-Lai, of the silkworm, Bombyx mori, and increase in cocoon characters was investigated such as cocoon weight, cocoon shell weight and cocoon shell ratio in males and females separately and cocoon filament length in mixed sex. The results showed that supplementation with either young or mature coconut water was effective for increase in cocoon characters in total 54 test points with two exceptions in which a cocoon shell ratio was less than 100 % against control in four times supplementation with mature coconut water in female in Nang-Noi and in two times supplementation with mature coconut water in male in Nang-Lai. The ratio of increase in cocoon characters was between 100.3 % and 112.3 %. These values were low compared to the results reported earlier using green coconut water in multivoltine silkworm variety. The reason was proposed that mulberry leaves of Sakhon Nakhon 72 were fed to the silkworm larvae in our study, which is the best quality of mulberry leaves in Thailand today and that it pushed the potential of the silkworm to produce cocoons to near the maximum and that a further increase in cocoon characters by supplementation with coconut water was minimal. Two times supplementation with young coconut water was effective for increase in cocoon shell ratio. Four times supplementation with mature coconut water was effective for increase in cocoon filament length. The reason was likely that difference in nutrient content between young and mature coconut water and the method of supplementation of two times or four times brought about increase in the specific cocoon character.