Pébrine

an infestation of various species of silkworm, including Bombyx mori, by the microsporidian Nosema bombycis.

Pébrine affects the silkworm in all stages of its development —ovum, caterpillar, pupa, and moth. The source of the causative agent is a silkworm suffering from the disease. Pébrine is transmitted by the excrement and carcasses of diseased silkworms, which contain spores of the causative agent. Caterpillars become infected upon swallowing the spores with food; the female moth transmits the agent to its offspring through the ova. Sick caterpillars do not eat, and their development is retarded. Punctate and larger black spots appear on the integuments. The silkworms construct their cocoons poorly and die at various ages. Diagnosis is established from the results of microscopic examination.

Control measures include heating the silkworm eggs at a temperature of 46°C for 30 minutes. After rearing the caterpillar, the premises should be disinfected.