Rangi disease of silkworm is caused by

Answer: Option A

Rangi disease of silkworm is caused by Serratia marcesens.
Serratia marcescens is a species of rod-shaped, Gram-negative bacteria in the family Yersiniaceae.
Rangi disease of silkworms is caused by bacteria Serratia marcesens. The bacterial diseases take a heavy toll on silkworm crop under high humidity. In Karnataka, the annual damage caused by this disease is 20 - 40%.
The spread and infection of disease are mainly by the consumption of contaminated leaves. The dead larvae release pathogens to the surrounding and many are survived in the environment (airborne) within the rearing house.