''Arthrobotrys dactyloides'' is a species of

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 ...

in the family Orbiliaceae. It is nematophagous, forming loops 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 or ...

to trap

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

s, on which it then feeds.

Description

The species has a whitish spreading

mycelium Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrate (biology), substrates. A typical single ...

of branched,

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

e (thread-like filaments) some 2 to 4 μm wide. The

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 ...

(non-motile spores) are borne on specialized stalks called conidiophores which are hyaline, erect and 200 to 550 μm long. These taper upwards and expand into a knob-like tip which is a distinguishing feature of this species. The conidia are hyaline, tapering towards the base and 20 to 52 μm long.

Biology

''A. dactyloides'' has the ability to form rings of

that can constrict sharply and catch a nematode in the loop. Each ring is a short branch of the hypha containing three cells, separated by three "T-shaped" areas of cell wall. When stimulated by the movement of a nematode inside the loop (or by heat, or by the tip of a researcher's needle), the three cells inflate suddenly, rather like balloons, and the nematode is trapped in a vice-like grip, its body constricted into two parts. Now branches of hypha invade the nematode on either side of the loop and digest and absorb the soft tissues. Within a few hours the nutrients from these are available to the mycelium of the fungus. Unlike some other species of

nematophagous fungi Nematophagous fungi are carnivorous fungi specialized in trapping and digesting nematodes. Around 160 species are known. There exist both species that live inside the nematodes from the beginning and others that catch them, mostly with glue tr ...

which create sticky nets, ''A. dactyloides'' is able to form constricting ring-traps immediately after emerging from the

. These are known as conidial traps and may constitute a survival mechanism under adverse conditions. Under normal conditions, a hypha is formed on germination of the conidia; this grows and branches to form a

, and loop traps form on the hyphae in the mycelium.

Uses

The fungus is being researched for use in biological control of root-knot nematodes. Compared to other nematophagous fungi it is rather slow growing. ''A. dactyloides'' has been mass-reared in liquid culture but because it is sensitive to desiccation, it has not been possible to use fast drying procedures. However, this problem has been overcome and it can now be formulated as granules which can be sprinkled on the soil close to plants. In greenhouse experiments it proved up to 96% effective at reducing root-knot nematodes.

References

{{Taxonbar, from=Q10418702 Ascomycota genera Orbiliales Fungi described in 1937