''Ampelomyces quisqualis'' is an

anamorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an ase ...

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

that is a

hyperparasite A hyperparasite, also known as a metaparasite, is a parasite whose host, often an insect, is also a parasite, often specifically a parasitoid. Hyperparasites are found mainly among the wasp-waisted Apocrita within the Hymenoptera, and in two othe ...

powdery mildew Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant diseases to identify, as ...

s. This parasitism reduces growth and may eventually kill the mildew. These mycoparasites can live up to 21 days on mildew-free host plant surfaces, attacking powdery mildew structures as soon as they appear. ''A. quisqualis'' is used as the active ingredient in a commercial fungicide.

Distribution and habitat

''Ampelomyces quisqualis'' has been shown to attack more than 64

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of powdery mildew in the genera '' Brasiliomyces'', ''

Erysiphe ''Erysiphe'' is a genus of fungi in the family Erysiphaceae. Many of the species in this genus are plant pathogens which cause powdery mildew. Species This genus includes, but is not limited to the following species: * ''Erysiphe alphitoides'' * ...

'', '' Leveillula'', ''

Microsphaera ''Microsphaera'' is a genus of powdery mildew Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales. Powdery mildew ...

'', ''

Phyllactinia ''Phyllactinia'' is a genus of fungi in the family Erysiphaceae. The type species is Phyllactinia suffulta. Species in this genus are plant pathogens, causing powdery mildew Powdery mildew is a fungal disease that affects a wide range of pla ...

'', ''

Podosphaera ''Podosphaera'' is a genus of fungi in the family Erysiphaceae. Species in this genus are plant pathogens, causing powdery mildew. Species *'' Podosphaera aphanis'' *'' Podosphaera balsaminae'' * ''Podosphaera clandestina'' var. ''aucupariae'' ...

'', '' Sphaerotheca'', and ''

Uncinula ''Uncinula'' is a genus of fungi. Its species are plant pathogens that cause powdery mildew diseases on various plant hosts. The genus is characterized by its dark chasmothecia which bear filamentous, hyaline appendages with hooked tips. Over ...

''. Powdery mildews in the order

Erysiphales Erysiphales are an order of ascomycete fungi. The order contains one family, Erysiphaceae. Many of them cause plant diseases called powdery mildew. Systematics The order contains one family (Erysiphaceae), 28 genera and approximately 100 speci ...

are widespread and varied. These powdery mildews occur in many countries around the world and have been recorded on 256 species of plant in 59 families.

Life cycle

''Ampelomyces quisqualis'' is a mycoparasite of powdery mildews. It overwinters or survives in the absence of a suitable host as

pycnidia A pycnidium (plural pycnidia) is an asexual fruiting body produced by mitosporic fungi, for instance in the order Sphaeropsidales ( Deuteromycota, Coelomycetes) or order Pleosporales (Ascomycota, Dothideomycetes). It is often spherical or inve ...

. Raindrops cause

conidia A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the ...

to be expelled from ripe pycnidia and these may splash onto nearby powdery mildew. Infection is favoured by humid conditions and temperatures in the range and may occur within 24 hours.

Hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

conidiophores A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to ...

and immature

cleistothecia An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are ...

can all be infected, the mycoparasite entering through the cell walls, and the previously transparent tissues turning milky-white. The infection spreads through the mildew colony for seven to ten days, after which time pycnidia begin to form. Their formation is complete in two to four days, when infected cells die, swelling considerably and turning brownish. Raindrops cause the release of conidia from the mature pycnidia which can cause secondary infections. There may be several generations of the mycoparasite during the growing season.

Uses

''Ampelomyces quisqualis'' is up to 98% effective in controlling the

Erysiphe cichoracearum ''Erysiphe cichoracearum'' is a fungal plant pathogen that causes powdery mildew disease of cucurbits, including melon, cucumber, pumpkin, and squash. The primary symptoms are white, powder-like spots on the leaves and stems. ''Sphaerotheca fu ...

'' on both young and old leaves of

cucumber Cucumber (''Cucumis sativus'') is a widely-cultivated Vine#Horticultural climbing plants, creeping vine plant in the Cucurbitaceae family that bears usually cylindrical Fruit, fruits, which are used as culinary vegetables.

. It is used to control ''

Podosphaera fuliginea ''Podosphaera fuliginea'' (also known as ''Podosphaera xanthii'') is a plant pathogen that causes powdery mildew on cucurbits. ''Podosphaera fuliginea'' and ''Erysiphe cichoracearum'' are the two most commonly recorded fungi causing cucurbit powd ...

'' on cucumber, another common cause of powdery mildew, but at the same time causes beige angular lesions on leaves and sunken greenish or tan lesions on fruit which reduces the value of the crop. The conidia of ''Ampelomyces quisqualis'' have been formulated and marketed in pellet and powder form as "AQ10". In the laboratory these were only partially efficient; they did not reduce the size of colonies of the powdery mildew ''

'' to any significant extent, but reduced the number of new infections initiated. However, acceptable disease control has been achieved in various greenhouse and field-grown crops. It is usually necessary to repeat the applications, and high humidity and raindrops assist in spreading the mycoparasite to new mildew colonies.

References

{{Taxonbar, from=Q2475964 Phaeosphaeriaceae Parasitic fungi Parasites of fungi Hyperparasites Fungi described in 1852