Nematophagous Hyphomycete Research Articles

NEMATOPHAGOUS FUNGI AGAINST STRONGYLATA LARVAE OF HORSES

Nematophagous hyphomycetes were found almost in all parts of the world and in different climatic zones. Therefore probably many researchers separate predatory fungi from all soil samples, wherever nematodes can exist. Currently, the prevention and treatment of nematodoses of herd horses by practicing veterinarians is limited to single deworming with the use of known semi-synthetic anthelmintic drugs. It should be noted that the strategy of anthelmintic treatment is aimed at disinfectation directly in the body of animals. Most anthelmintic drugs have antiparasitic properties, and are highly toxic to any endothermic organism. Chemical components of antiparasitic drugs after animal use are excreted in the environment with feces, and, being practically unchanged, continue their strong toxic effect on the pasture biocenosis components. The nematophagous fungi isolated from the permafrost soil of Yakutia belong to the genus Arthrobotrys according to the description of the species, and by morphological and physiological characteristics; 2 strains of predatory fungi L3-1 and L3-2 have been identified. Nematophagous fungi of the genus Arthrobotrys occupy a certain place in the system of microbiomes that are able to control nematodes.

Effect of Pochonia chlamydosporia-based formulates on the regulation of root-knot nematodes and plant growth response

ABSTRACTEU legislation restricted many chemicals for root-knot nematodes (Meloidogyne spp., RKNs) control. Alternative ways of plant protection were hence investigated, based on the use of microbial formulations exploiting plant parasites antagonism. RKNs are severe and widespread pests causing extensive damage to crops in greenhouse and field. Several antagonistic microorganisms are suitable for biocontrol, including the nematophagous hyphomycete Pochonia chlamydosporia that parasitizes eggs to acquire additional nourishment and face competition with other soil microorganisms. A commercial product (POCHAR) was developed by Microspore based on P. chlamydosporia with other microbial inocula that can be applied through irrigation. The aim of this study was to test POCHAR’s efficacy against RKNs on potato and its promotion effect on tomato in two field trials. Moreover, the research included trials to evaluate the best method for open-field application in crops not managed through drip irrigation, opening up the possibility to treat large areas without major technological needs. RKNs control with POCHAR represented a viable alternative to chemicals. In conclusion, the organic approach developed through the bioformulated product highlighted effective RKNs management, with a potential to sustain both plant nutrition and the related root protection needs.

Arthrobotrys latispora, a new nematode-trapping fungus from southwest China

Using morphology and molecular phylogenetic analyses, we report a new nematophagous hyphomycete species, Arthrobotrys latispora, which produces erect, branched or unbranched conidiophores with conspicuous nodes at the tip; the conidia are nonseptate (41%) or uniseptate (59%) and broadly ovoid to oval. Three-dimensional adhesive networks formed in the presence of nematodes.

Histology of the interactions of Paecilomyces lilacinus with Meloidogyne incognita on Eclipta alba (L.)

Under greenhouse conditions, the experiment was conducted to test the efficacy of opportunistic and nematophagous hyphomycete, Paecilomyces lilacinus against root-knot nematode, Meloidogyne incognita on Eclipta alba. The treatment comprised inoculation of E. alba with M. incognita alone (N) and in combination with P. lilacinus (one week before (T1), simultaneously (T2), one week after (T3), two weeks after (T4) and three weeks after (T5)). The results showed that the application of P. lilacinus before one week of nematode inoculation (Tl) was more effective than other treatments. A significant enhancement was noticed in the growth and yield of E. alba. Root-knot and egg mass indices were suppressed due to destruction of the mature females and the egg masses. Histopathological studies revealed the presence of P. lilacinus hyphae in and around the females and the eggs.

Orbilia querci sp. nov. and its knob-forming nematophagous anamorph

Orbilia querci, a new nematode-trapping fungus, was found on rotten wood of Quercus sp. in Huai-rou County, Beijing, China. It is characterized by having a tear-shaped spore body in the cylindrical ascospore. Pure culture was obtained from the ascospores. Conidiophores were simple or occasionally branched, bearing a single conidium on the tip. Conidia were spindle-shaped, mostly with 3-septa. Nematodes were captured by means of adhesive stalked knobs. The adhesive knobs were produced frequently on nutritional agar plates even in the absence of challenging nematodes. Its anamorph is placed in Dactylellina and named as D. querci. The sequence divergence of the ITS1 region between the fungus and the other knob-forming species tested was 23.8–33.4%, supporting O. querci as a distinct species. This is the first report of the connection between a knob-forming nematophagous hyphomycete and an Orbilia teleomorph.

Capture of mites and rotifers by four strains of Dactylella gephyropaga known as a nematophagous hyphomycete

Four strains of Dactylella gephyropaga obtained from Japan and Indonesia captured mites, as well as nematodes, by means of the adhesive hyphal network composed of columnar processes and rectangular meshes of hyphae, in which each of the meshes was made by additional growth of apex of a columnar process toward that of neighboring process and anastomosis with each other. This is the first report showing that a fungus captured and consumed mites. When immersed under water, the four strains captured rotifers also with the columnar processes by adhesion. The CBS178.37 used for comparison was not the strain of D. gephyropaga, and its adhesive network was produced only by repeating development and anastomosis of curved hyphae that captured neither mites and rotifers but only nematodes.

The nematophagous hyphomycete Esteya vermicola found in the Czech Republic.

The nematophagous hyphomycete <i>Esteya vermicola</i> found in the Czech Republic.

Phylogenetic relationship of Cephaliophora to nematophagous hyphomycetes including taxonomic and nomenclatural emendations of the genus Lecophagus

The rotifer-capturing fungus Cephaliophora muscicola has many systematic and nomenclatural problems. It was described originally as Lecophagus fasciculatus and classified as a Zygomycete. To address the systematic position of this fungus and to infer the phylogenetic relationsips within other hyphomycetes, we determined and analyzed 18S rDNA sequences of C. muscicola and several of its predacious and nonpredacious relatives. Our phylogenetic analyses indicate that C. muscicola forms a monophyletic clade with nematophagous hyphomycetes, such as Arthrobotrys spp. This result indicates that the predacious nature of these fungi might be plesiomorphic for this lineage. The nonpredacious species of Cephaliophora, including the type species C. tropica, are distandy related to this lineage. Therefore the rotifer-capturing species of Cephaliophora, C. muscicola and C. longispora, are transferred to the anamorphic genus Lecophagus, and we have emended the genus accordingly.

Phylogenetic Relationship of Cephaliophora to Nematophagous Hyphomycetes Including Taxonomic and Nomenclatural Emendations of the Genus Lecophagus

The rotifer-capturing fungus Cephaliopho- ra muscicola has many systematic and nomenclatural problems. It was described originally as Lecophagus fasciculatus and classified as a Zygomycete. To ad- dress the systematic position of this fungus and to infer the phylogenetic relationsips within other hy- phomycetes, we determined and analyzed 18S rDNA sequences of C. muscicola and several of its preda- cious and nonpredacious relatives. Our phylogenetic analyses indicate that C. muscicola forms a monophy- letic clade with nematophagous hyphomycetes, such as Arthrobotrys spp. This result indicates that the pre- dacious nature of these fungi might be plesiomor- phic for this lineage. The nonpredacious species of Cephaliophora, including the type species C. tropica, are distantly related to this lineage. Therefore the rotifer-capturing species of Cephaliophora, C. musci- cola and C. longispora, are transferred to the ana- morphic genus Lecophagus, and we have emended the genus accordingly.

Arthrobotrys hertziana sp. nov. from the Canary Islands

A new nematophagous hyphomycete is described from the Canary Islands as Arthrobotrys hertziana. It has branched conidiophores with slightly swollen tips, mostly three-septate conidia, and sticky knobs as trapping devices. A key to Arthrobotrys species forming sticky knobs is presented. Among six nematode and two springtail species tested as hosts only the nematode Panagrellus redivivus was trapped. The results are discussed with reference to taxonomical problems and the possibly limited host range.

A new nematophagous species of Verticillium from China

Verticillium sinense sp. nov., a nematophagous hyphomycete with small, acorn-shaped conidia adhering in slimy heads and in dry chains is described.

Two Arthrobotrys Anamorphs from Orbilia auricolor

Cultures derived from ascospores of two collections both referable to Orbilia auricolor produced anamorphs which were assigned to Arthrobotrys cladodes var. macroides and A. oligospora var. oligospora. These morphologically distinct isolates formed nematode-capturing hyphal networks when nematodes were present. Descriptions of the Arthrobotrys isolates are given. At least one other nematophagous hyphomycete is connected with a teleomorph that can be referred to O. auricolor suggesting that O. auricolor is not a single entity but a species complex.

An electron microscope study of initiation of infection by conidia of Harposporium oxycoracum, an endozoic nematophagous Hyphomycete

Infective conidia of an endozoic nematophagous hyphomycete, Harposporium oxycoracum Drechsler, were examined by means of electron microscopy. Each of the conidia is very narrow and has a sharply pointed distal and slightly swollen basal end. The swollen basal end was shown, in ultrathin sections stained with ruthenium red en bloc, to be an electron-dense mass of fibrils (ca. 2–3 μm in diameter). The fibrils, thought to be derived from the conidial cell wall, were densely aggregated and were surrounded by a network of more sparsely aggregated fibrils spreading from the fibrous mass of the conidial base. The spreading fibrils seemed to correspond to the mucous droplet observed under the light microscope. It was also found in the present study that the conidia of the fungus were swallowed by nematodes into their lower gut. On germination in the lower gut, a narrow germ tube 5–6 μm wide developed from the convex side of the conidium and produced a simple pore septum at the site of penetration to delimit the empty conidium.

Nematophagous Hyphomycetes: observations on Harposporium helicoides

The conidia of endoparasitic nematophagous Hyphomycetes ingested by nematodes lodge in either the buccal cavity or the oesophageal lumen. In H. helicoides, however, nematodes have little difficulty in swallowing the conidia, and infection is initiated by the conidia germinating in the gut. The characteristics of H. helicoides in culture are given.

Isolation and maintenance of endoparasitic nematophagous Hyphomycetes

A technique has been developed using differential centrifugation which allows the isolation of endoparasitic nematophagous Hyphomycetes belonging to the genera Harposporium, Meria, Nematoctonus, and Verticillium. Both ingested and adhesive parasites have been isolated by this technique. The method eliminates most of the large-spored predaceous species which usually complicate the recovery of endoparasites. Methods for maintaining endoparasitic fungi in association with nematodes or in pure culture are described.

RELATION OF SOME ENVIRONMENTAL FACTORS TO GROWTH OF SEVERAL NEMATOPHAGOUS HYPHOMYCETES

In vitro growth studies showed that Arthrobotrys oligospora Fresenius, A. conoides Drechsler, A. musiformis Drechsler, and A. robusta Duddington are characterized by a fast, inherent growth rate relative to A. dactyloides Drechsler, Dactylella gephyropaga Drechsler, and Dactylaria brochopaga Drechsler, which grew slowly on all media tested. Arthrobotrys superba Corda, Dactylella ellipsospora Grove, and D. asthenopaga Drechsler were found to be intermediate in this respect. There was little correlation between the maximum rate of increase in colony diameter of the 10 species of nematophagous Hyphomycetes and their ecological requirements for such growth. The fast-growing species appeared to prefer media with a pH range of 5.0–6.0 and the slow-growing fungi a pH of about 4.0. No consistent similarity in environmental requirements was found among species of fungi belonging to the same genus or between those possessing the same kind of nematode-trapping organ. Lima bean agar of pH 5.0 was a satisfactory culture medium and incubation at 25 °C in continuous or intermittent light resulted in larger colonies than incubation in darkness.

A chemically defined medium for the cultivation of nematophagous hyphomycetes

The medium, suitable for the cultivation of certain nematophagous hyphomycetes, consists of maltose, MgSO 4 .7H 2 O, KH 2 PO 4 , KCl, FeSO 4 .7H 2 O and NaNO 3 , and provides for growth equivalent to that produced by the organisms on natural media. Sporulation is favoured by the addition of 50 mg./l. of meso-inositol.