Some Observations on Phenotypic Variations in Mulberry Silkworm, Bombyx mori L.

Kolar gold (PM${\times}$CSR2) is the most popular cross breed of India, especially in Karnataka. During January - February 2004 we observed several phenotypic variations leading to poor survival. Though occurrence of morphologically abnormal individuals is common, the extent of occurrence in the present report was on the higher side (upto 6 percent). It is unwarranted and not desirable in commercial silkworm rearing. The variations exhibited might be due to change in the environmental conditions like incubation temperature during embryonic stage or spontaneous mutation resulting out of environmental stress.