Conidia of the nematophagous fungus Drechmeria coniospora adhere to but barely infect Acrobeloides buetschilii (original) (raw)
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Infection of nematodes by conidia of Drechmeria coniospora was studied by optical-and electron microscopy. After penetration, trophiC hyphae invaded solely via the pseudocoel; penetration of internal organs was never observed. The invading hyphae had a characteristic wave-like appearance, this pattern possibly having the advantage of preventing rupture of hyphae due to host movements. After death of the host 30-48 h after infection, trophic hyphae contained numerous lipid droplets often associated with microbodies (peroxisomes) which were characterized by the presence of catalase and the l3-oxidation enzyme thiolase. Conidiophores developed from tips of trophiC hyphae; the process of outgrowth being similar to that for initial penetration in that it occurred via enzymic action and mechanical force. Intimate association between fungal cell wall and nematode cuticle suggested that leakage of nematode contents was prevented after outgrowth. Conidiophores possessed an electron dark layer at the outside of their wall which was not continuous with developing conidia. Numerous spores were successively formed from each individual peg present on the conidiophore. Pegs were ordered at regular distances, located in close proximity to septa and on the apical end of the conidiophore. Invariably immature spores are formed; development of the adhesive knob occurred after release from the peg. Approximately 5000-10000 spores were formed at the expense of a single nematode.
Journal of Invertebrate Pathology, 1989
Third-stage infective juveniles (dauers) in the nematode genera Steinernema and Heterorhabditis are ensheathed in their second-stage (52) cuticles. Retention of the 32 cuticle by various species and strains of Steinernema and Heterorhabditis was determined after the dauers moved through 5 cm of sand. In general, Heterorhabditis spp. (89-100%) retained their 52 cuticles whereas Steinernema spp. (100%) lost theirs. When dauers of Steinernema and Heterorhabditis spp. with and without 52
Applied and Environmental Microbiology, 1985
The conidia of the endoparasitic fungus Meria coniospora ( Deuteromycetes ) had different patterns of adhesion to the cuticles of the several nematode species tested; adhesion in some species was only to the head and tail regions, on others over the entire cuticle, whereas on others there was a complete lack of adhesion. After adhesion, the fungus usually infected the nematode. However, adhesion to third-stage larvae of five animal parasitic nematodes, all of which carry the cast cuticle from the previous molt, did not result in infection. M. coniospora infected animal parasitic nematodes when this protective sheath was removed. Seven preparations of sialic acid ( N -acetylneuraminic acid) gave three types of response in adhesion-infection of nematodes: (i) a significant reduction in conidial adhesions; (ii) no interference with adhesion, but a 10-day delay in infection; and (iii) a delay in infection by 2 to 3 days. The current results support previous findings indicating involveme...
The infection of nematodes by the endoparasitic fungus Verticillium balanoides was studied by means of optical and electron microscopical techniques. Conidia of this fungus adhere randomly in high numbers to the entire cuticle surface of the nematode Panagrellus redivivus. Adhesion is accomplished by means of a tri-layered adhesive pad located at the apical end of the conidium, the outermost layer of which shows a radiated substructure. After attachment an appressorium which grows through the adhesive pad and establishes a firm contact between the fungal cell wall and the nematode cuticle is formed. Penetration of the cuticle by means of a hyphal outgrowth on the appressorium is followed by the formation of an infection bulb from which trophic hyphae develop that invade the nematode. Approximately 60 h after infection conidiophores develop outside the nematode, producing numerous conidia.
International Journal for Parasitology, 1987
The adhesion of conidia of the fungus LXlophospora alopecuri to the surface of the second stage dauer larva (DL:) of the nematode Anguina agrostis (syn. A. jimesta) was examined using both light and electron optics. The process of attachment does not lead to any apparent damage to the epicuticle of the nematode. Photographs of sections cut tangentially through the setulose appendages of the conidia show that a mucilagenous fibrillar material appears to be exuded from the highly convoluted surface of these appendages. This material adheres to the surface of the nematode cuticle and is deposited in the transverse annulations. The adhesion of these spores to DL2 of A. agrostis was examined in 4822 nematodes from four galls. The mean percentage of DL? with spores adhering was 64% and ranged from 43 to 85%. This adhesion was compared with that of Corynebucterium ruthuyi from bacterial galls and was found to coincide. Thus, bacteria adhere to nematodes with I). alopecuri conidia attached and these conidia adhere to nematodes with C. rathayi attached. Furthermore, DLZ that are free from conidial adhesion appear to be free from bacterial adhesion and, in most instances, DL2 that remain from from bacterial adhesion remain free from conidial adhesion. These observations draw attention to the potential of LI. alopecuri as an agent for the biological control of annual ryegrass toxicity. Conidial adhesion to A. ugrosris differs from bacterial adhesion to this nematode in that no visible damage to the cuticle takes place. The concept that adhesion of microorganisms to nematodes occurs in two phases, one involving site recognition and the other. if it occurs, involving physiological interaction and morphological change is discussed.
Nematophagous Fungi as an Extraordinary Tool to Control Parasitic Nematodes: A Review
Environmental Science Archives, 2023
Due to the harmful impacts of using chemicals in controlling plant pests as nematodes, there is a current trend of employing natural pesticides that show potency together without contaminating the environment or negatively affect human and other creatures. Hence, the name of nematophagous fungi has risen as potent biocontrol tools that attack nematodes specifically without harming surrounding ecosystem. Different nematophagous fungal species act as natural predators of nematodes and soil-dwelling worms. Hence, we aimed in this review to discuss importance of nematophagous fungi, their occurrence, taxonomy and evolution. Also, describing examples of using nematophagous fungi as biological control agents. Moreover, the future of employing nematophagous fungi in general and mushrooms in particular in this field is highlighted.
Applied Entomology and Zoology, 2004
Infectivity and post-infection development were investigated at 25°C for infective juveniles (IJs) which originated via endotokia matricida in hermaphrodites and/or female adults of the entomopathogenic nematodes, Heterorhabditis bacteriophora, Steinernema glaseri and S. carpocapsae. The IJs spontaneously emerging out of larval cadavers of Galleria mellonella were designated as normal IJs and used as comparison. Nematode invasion was the most prompt and numerous for normal IJs, followed by IJs produced via endotokia matricida in the 1st, 2nd, and 3rd generation adults of the three nematode species examined. Post-infection development and reproduction of nematodes also occurred more promptly and numerously when inoculation was made with normal IJs. The insecticidal activity of IJs originating from endotokia matricida was inferior to that of normal IJs which retained a significantly higher density of symbiotic bacteria than the former IJs of the respective nematode species. The IJs reproduced in and emerged out of host cadavers showed similar pathogenicity and bacterial retention, irrespective of the origin of the IJs used as inocula.
2007
This review discusses the taxonomy, patterns of sporogenesis and modes of infection of a group of little studied holocapic pathogens of bactivorous nematodes (and rotifers) from terrestrial and marine habitats. These holocarpic obligate parasites have been traditionally placed within the "Iagenidiaceous oomycetes" although Haptoglossa had been placed in the Saprolegniales. The nematode pathogens that will be discussed fall within the genera C/amydomyzium, Gonimocheate, Haptoglossa and Myzocytiopsis. The patterns of asexual and sexual sporogenesis will be described in detail in the light of recent ultrastructural studies that we have undertaken. We conclude by discussing the main infection strategies employed by these organisms which we categorise into active and passive types. In the former, zoospores actively locate their host (by chemotaxis) and encyst on the host surface immediately prior to infection. In the latter types, the zoospores or aplanospores rapidly germinate...
Journal of Agricultural Science and Technology, 2008
The reproductive range of the Iranian population of white tip nematode in rice, Aphelenchoides besseyi, was investigated in vitro to find out a suitable medium as well as a favorable fungal host for monoxenic culturing this nematode. Studies were carried out on rice seed associated fungi, pathogenic fungi and one mushroom (Agaricus bisporus) grown on three culture media, RPA (rice polish agar), OMA (oat meal agar) and PDA (potato dextrose agar). The nematode showed the greatest multiplication on Fusarium verticillioides, F. proliferatum, Curvularia lunata and Magnaporthe salvini in OMA and on Alternaria alternata, Bipolaris oryzae and Pyricularia oryzae in PDA. Among the fungi, tested A. alternata, C. lunata, F. verticillioides, B. oryzae, M. salvini, F. proliferatum and P. oryzae supported a high reproduction rate in the nematode in a descending rank. The nematode failed to multiply on Aspergillus niger, Rhizoctonia solani and Agaricus bisporus grown on any of the three media. The highest sex ratio (F:M) was achieved on OMA but the highest male percentage ratio was observed on PDA. The two pathogenic fungi, B. oryzae and M. salvini are reported as new fungal hosts for monoxenic culturing of this nematode.