''Aschersonia aleyrodis'' is a

fungal A fungus (: fungi , , , or ; 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 one of the tradit ...

pathogen affecting various species of

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

. It has been shown to control the

silverleaf whitefly The silverleaf whitefly (''Bemisia tabaci'', also informally referred to as the sweet potato whitefly) is one of several species of whitefly that are currently important agricultural pests. A review in 2011 concluded that the silverleaf whitefly ...

(''Bemisia tabaci'') in laboratory and greenhouse conditions.

Description

The stroma of ''Aschersonia aleyrodis'' forms a hemispherical or cushion-shaped mass about wide and high, surrounded by a thin ring of

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 o ...

e that spreads across the leaf-surface. The

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 ...

-forming zones consist of shallow pits in the stroma with pore-like openings. The conidia are elongated and cigar-shaped, and do not have septa. This fungus is cream, pink or pale orange, and the massed conidia are darker orange. The

teleomorph 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 ...

of this fungus is '' Hypocrella''.

Biological control of whitefly

Whitefly Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described. Description and taxonomy The A ...

are an increasing pest of greenhouse crops such as cucumber and tomato. The classical biological control is by the use of parasitoid wasps such as '' Encarsia formosa '', but aggressive strains of whitefly have emerged and results are unpredictable. Another approach is with the use of entomopathogenic fungi such as ''Aschersonia aleyrodis'' and this has met with some success, the main target insect being

greenhouse whitefly ''Trialeurodes vaporariorum'', commonly known as the glasshouse whitefly or greenhouse whitefly, is an insect that inhabits the world's temperate regions. Like various other whiteflies, it is a primary insect pest of many fruit, vegetable and or ...

(''Trialeurodes vaporariorum''). Infectivity and persistence is greater on some crops than others. Germination of

tends to be low on the leaves, but the conidia remain viable there for a month or more, as can be shown by washing them off with water onto an

agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from " ogonori" and " tengusa". As found in nature, agar is a mixture of two components, t ...

plate. Infectivity of whitefly nymphs was highest on cucumbers (90%) at 31 days, whereas on

gerbera ''Gerbera'' ( or ) L. is a genus of plants in the Asteraceae (Compositae) family. The first scientific description of a ''Gerbera'' was made by J. D. Hooker in Curtis's Botanical Magazine in 1889 when he described '' Gerbera jamesonii'', a S ...

s it was 80% initially but had decreased to 40% by day 31, and on

poinsettia The poinsettia (; ''Euphorbia pulcherrima'') is a commercially important flowering plant species of the diverse spurge family Euphorbiaceae. Indigenous to Mexico and Central America, the poinsettia was first described by Europeans in 1834. It ...

, germination capacity of the conidia was still 60% at 31 days after application, but nymphal mortality, initially 70%, fell to 10% after three days and remained low for the rest of the month. The pathogen is an effective biocontrol agent for

under the conditions found in greenhouse and laboratory.

References

{{Taxonbar, from=Q10419255 Parasitic fungi Clavicipitaceae Fungus species