Flacherie

Definition

A viral disease of silkworms (Bombyx mori) caused by the Infectious flacherie virus (IFV), a positive-sense single-stranded RNA virus in the family Iflaviridae. The disease manifests as systemic weakness, flaccid paralysis, and dark brown discoloration in terminal larvae, typically transmitted through ingestion of contaminated mulberry leaves. Historically, flacherie was a major cause of mortality in sericulture and was often conflated with similar bacterial or nutritional disorders until viral etiology was established.

Etymology

French, from flacher 'to weaken, become flaccid', describing the limp, weakened appearance of affected larvae

Example

In 19th-century French sericulture, outbreaks of flacherie could destroy entire crops of Bombyx mori, with larvae showing the characteristic flaccid paralysis and chocolate-brown coloration before death; modern management relies on virus-free stock and mulberry leaf disinfection.

Synonyms

• infectious flacherie
• viral flacherie
• IFV infection

Related Terms

• pebrine
• grasserie
• Cytoplasmic polyhedrosis virus
• Sericulture
• Bombyx mori
• Iflaviridae
• invertebrate pathology
• picorna-like virus

Usage Notes

The term 'flacherie' has been used historically for multiple silkworm diseases with similar symptoms, including bacterial (primarily Serratia marcescens) and nutritional forms. In modern usage, it should be qualified as 'infectious flacherie' or 'viral flacherie' when referring specifically to the Iflavirus disease. The unqualified term remains common in historical and sericultural literature. Contrast with 'pebrine' (microsporidian disease) and 'grasserie' (nuclear polyhedrosis virus), which show different symptoms and etiologies.