Effect of various levels of dietary cholesterol on cocoon production and reproduction of the silkworm, Bombyx mori L.

Abstract

When fifth-instar larvae of the silkworm were reared on a synthetic diet containing 1.6-4.0mg cholestrol per g dry diet, normal larval growth was obtained. When the cholesterol content was below 0.8mg per g dry diet, however, the larval growth and the weight of cocoon and cocoon-layer were reduced. Only a part of the larvae pupated and became adults. When larvae were fed on a cholesterol-deficient diet, all of them could neither make coccoon nor pupate. Cholesterol content of the larval hemolymph was proportional to the level of dietary cholesterol.
The minimum level of cholesterol required for the normal oviposition was about 1.6mg per g dry diet. The number of eggs laid rather than the weight of eggs was more affected by the level of cholesterol.
Cholesterol content of the eggs increased markedly when the dietary cholesterol level was raised from 0.2 to 1.6mg per g of dry diet. When the dietary level was further increased, however, the cholestrol content of eggs was only slightly increased. Furthermore, the total lipid content of eggs was virtually not varied, even when dietary level of cholesterol was changed.