Flacherie (literally: "flaccidness") is a disease of
silkworm
''Bombyx mori'', commonly known as the domestic silk moth, is a moth species belonging to the family Bombycidae. It is the closest relative of '' Bombyx mandarina'', the wild silk moth. Silkworms are the larvae of silk moths. The silkworm is of ...
s, caused by silkworms eating infected or contaminated
mulberry
''Morus'', a genus of flowering plants in the family Moraceae, consists of 19 species of deciduous trees commonly known as mulberries, growing wild and under cultivation in many temperate world regions. Generally, the genus has 64 subordinat ...
leaves. Flacherie infected silkworms look weak and can die from this disease. Silkworm larvae that are about to die from flacherie are a dark brown.
There are two kinds of flacherie: essentially, infectious (viral) flacherie and noninfectious (''touffée'') flacherie. Both are technically a lethal
diarrhea
Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...
.
Touffée flacherie is caused by
heat wave
A heat wave or heatwave, sometimes described as extreme heat, is a period of abnormally hot weather generally considered to be at least ''five consecutive days''. A heat wave is usually measured relative to the usual climate in the area and ...
s.
Viral flacherie is ultimately caused by infection with
''Bombyx mori'' infectious flacherie virus (BmIFV,
Iflaviridae),
''Bombyx mori'' densovirus (BmDNV,
Parvoviridae
Parvoviruses are a family of animal viruses that constitute the family ''Parvoviridae''. They have linear, single-stranded DNA (ssDNA) genomes that typically contain two genes encoding for a replication initiator protein, called NS1, and the pr ...
) or
''Bombyx mori'' cypovirus 1 (BmCPV-1,
Reoviridae
''Reovirales'' is an order of double-stranded RNA viruses. Member viruses, called reoviruses, have a wide host range, including vertebrates, invertebrates, plants, protists and fungi. They lack lipid envelopes and package their segmented geno ...
). This either alone or in combination with
bacteria
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
l infection destroys the
gut tissue. Bacterial
pathogen
In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
s contributing to infectious flaccherie are ''
Serratia marcescens
''Serratia marcescens'' () is a species of bacillus (shape), rod-shaped, Gram-negative bacteria in the family Yersiniaceae. It is a facultative anaerobe and an opportunistic pathogen in humans. It was discovered in 1819 by Bartolomeo Bizio in Pa ...
'', and species of ''
Streptococcus
''Streptococcus'' is a genus of gram-positive spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs along a sing ...
'' and ''
Staphylococcus
''Staphylococcus'', from Ancient Greek σταφυλή (''staphulḗ''), meaning "bunch of grapes", and (''kókkos''), meaning "kernel" or " Kermes", is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillale ...
'' in the form known as ''thatte roga''.
In the nineteenth century, flacherie resisted the efforts of
Louis Pasteur
Louis Pasteur (, ; 27 December 1822 – 28 September 1895) was a French chemist, pharmacist, and microbiologist renowned for his discoveries of the principles of vaccination, Fermentation, microbial fermentation, and pasteurization, the la ...
.
[G. Balbiani, ''Leçons sus les sporozoaires'', Paris, 1884, p. 160-163 and 167-168]
online
References
Insect viral diseases
Diseases of Lepidopterans
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