Abstract
When a definite amount of the filtrate obtained from the haemolymph of an infected larva of the silkworm or from the culture of Spicaria prasina (MAUBLANC) SAWADA was injected into the 3rd- or 4th-instar larvae of the silkworm belonging to the four-molter hybrid, many larvae became precocious pupae without larval molting. The ratio of precocious pupae was higher when the filtrate was injected to the younger larvae than the older. On the contrary, either pupation from the 5th-instar larva or emergence from the pupa was inhibited by the injection of filtrate of the fungus culture. The active substance in the culture filtrate was extracted from water layer with organic solvents, such as ether, chloroform, petroleum ether, and n-butanol. While, the substance could not be extracted with methanol, ethanol, and ethylacetate, and was precipitated with acetone. The substance was inactivated by heating at 50°C for 10min, even though no activity was lost following the treatment with buffer solution at pH 1.7 or 9.7 at about 23°C for 1hr.
