Entomophaga Maimaiga
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''Entomophaga maimaiga'' is a Japanese fungus which has shown striking success in managing
spongy moth ''Lymantria dispar'', also known as the gypsy moth or the spongy moth, is a species of moth in the family Erebidae native to Europe and Asia. ''Lymantria dispar'' is subdivided into several subspecies, with subspecies such as '' L. d. dispar'' ...
populations in North America.


Etymology

''Maimaiga'' is the Japanese name for the spongy moth.


History

In 1908, shortly after classical efforts began to control
spongy moth ''Lymantria dispar'', also known as the gypsy moth or the spongy moth, is a species of moth in the family Erebidae native to Europe and Asia. ''Lymantria dispar'' is subdivided into several subspecies, with subspecies such as '' L. d. dispar'' ...
populations, North American researchers studied cadavers of Japanese spongy moths which had been killed by an entomophthoralean fungus. The fungus was released in the Boston area between 1910 and 1911. By 1912, they summarized their work, stating that extensive releases had never established this fungal pathogen, which they referred to as "gypsy fungus". In the early 1980s, another attempt was made to introduce ''Entomophaga maimaiga'' into the wild. They obtained the sample from the western coast of
Honshu , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...
. The fungus was determined to belong to the genus '' Entomophaga'' in the fungal order
Entomophthorales The Entomophthorales are an order of fungi that were previously classified in the class Zygomycetes. A new subdivision, Entomophthoromycotina, in 2007, was circumscribed for them. Most species of the entomophthorales are pathogens of insects ...
and was given the name ''maimaiga'' based on geographical distribution. In 1985 and 1986 were made small-scale releases of laboratory spongy moth larvae injected with fungal cells. The locations were
New York State New York, also called New York State, is a state in the northeastern United States. Bordered by New England to the east, Canada to the north, and Pennsylvania and New Jersey to the south, its territory extends into both the Atlantic Ocean and ...
and
Shenandoah National Park Shenandoah National Park (often ) is a List of national parks of the United States, national park of the United States that encompasses part of the Blue Ridge Mountains in Virginia. The park is long and narrow, with the Shenandoah River and its ...
respectively. At the time these releases were not considered to be successful. In 1989, cadavers of spongy moths found hanging on tree trunks revealed large resting spores characteristic of entomophthoralean fungi. The fungus found appeared to be the same species as released in 1910, 1911, 1985 and 1986. The fungus spread across spongy moth populations over the next several years.


Method of dispersion

The fungus spreads through aerial dispersion of actively ejected asexual spores from cadavers of spongy moth larvae it has killed. It can also be spread unwittingly by humans. The fungus persists in the top layer of soil as resting spores. These have been shown to persist for at least 11 or 12 years, probably longer.


Effect on spongy moths

The fungus causes high levels of infection among spongy moths in both low and high density populations, leading to population crashes. Early instars of infected moths typically eject
conidia A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...
when they die in tree canopies, further infecting later instars containing spores of the fungus but no outward fungal growth.


Effect on non-target Lepidoptera

''Entomophaga maimaiga'' can only potentially affect lepidopteran larvae that are present in the spring, when spongy moth larvae are present. 78 species which fit this criterion were tested. Only about one-third were able to be infected under optimal conditions. Infection was only consistently high among three species of
tussock moth The Lymantriinae (formerly called the Lymantriidae) are a subfamily of moths of the family Erebidae. The taxon was erected by George Hampson in 1893. Many of its component species are referred to as "tussock moths" of one sort or another. The ca ...
s and one colony of a
hawk moth The Sphingidae are a family of moths commonly called sphinx moths, also colloquially known as hawk moths, with many of their caterpillars known as hornworms. It includes about 1,450 species. It is best represented in the tropics, but species ar ...
. However, field studies showed that rates achieved in the laboratory are far higher than found in the field. Overall the pathogen is considered highly host specific.


References

{{Authority control Fungal pest control agents Fungi described in 1988 Fungi of Asia Entomophthorales Parasitic fungi Fungus species