Paecilomyces lilacinus is a common saprobic, filamentous fungus. It has been isolated from a wide range of habitats including cultivated and uncultivated soils, forests, grassland, deserts, estuarine sediments and sewage sludge. It has also been found in nematode eggs, and occasionally from females of root-knot and cyst nematodes. In addition, it has frequently been detected in the rhizosphere of many crops. The species can grow at a wide range of temperatures – from 8°C to 38°C for a few isolates, with optimal growth in the range 26°C to 30°C. It also has a wide pH tolerance and can grow on a variety of substrates. P. lilacinus has shown promising results for use as a biocontrol agent to control the growth of destructive root-knot nematodes.
P. lilacinus used to be classified with the Fungi Imperfecti or Deuteromycetes, fungi for which perfect (i.e., sexually reproducing) states have rarely been found. Paecilomyces lilacinus was classified in the section Isarioidea, for which perfect states have not been found. Many isolates of P. lilacinus have been identified from around the world and it is accepted that variation exists within the species. It is now accepted that it should be placed in the family Trichocomaceae (Ascomycota). Phylogenetic analysis of P. lilacinus isolates show that it is more closely related to Trichoderma, Gliocladium and Hypocrea than to the other entomopathogenic Paecilomyces species in the Hypocreales.
P. lilacinus forms a dense mycelium which gives rise to conidiophores. These bear phialides from the ends of which spores are formed in long chains. Spores germinate when suitable moisture and nutrients are available. Colonies on malt agar grow rather fast, attaining a diameter of 5–7 cm within 14 days at 25°C, consisting of a basal felt with a floccose overgrowth of aerial mycelium; at first white, but when sporulating changing to various shades of vinaceous. The reverse side is sometimes uncolored but usually in vinaceous shades. The vegetative hyphae are smooth-walled, hyaline, and 2.5–4.0 µm wide. Conidiophores arising from submerged hyphae, 400–600 µm in length, or arising from aerial hyphae and half as long. Phialides consisting of a swollen basal part, tapering into a thin distinct neck. Conidia are in divergent chains, ellipsoid to fusiform in shape, and smooth walled to slightly roughened. Chlamydospores are absent.
P. lilacinus is highly adaptable in its life strategy: depending on the availability of nutrients in the surrounding microenvironments it may be entomopathogenic, mycoparasitic, saprophytic, as well as nematophagous.
P. lilacinus is an infrequent cause of human disease. Most reported cases involve patients with compromised immune systems, indwelling foreign devices, or intraocular lens implants. Research of the last decade suggests it may be an emerging pathogen of both immunocompromised as well as immunocompetent adults.
Plant-parasitic nematodes cause significant economic losses to a wide variety of crops. Chemical control is a widely used option for plant-parasitic nematode management. However, chemical nematicides are now being reappraised in respect of environmental hazard, high costs, limited availability in many developing countries or their diminished effectiveness following repeated applications.
Control of plant-parasitic nematodes
P. lilacinus was first observed in association with nematode eggs in 1966 and the fungus was subsequently found parasitising the eggs of Meloidogyne incognita in Peru. It has now been isolated from many cyst and root-knot nematodes and from soil in many locations. Several successful field trials using P. lilacinus against pest nematodes were conducted in Peru. The Peruvian isolate was then sent to nematologists in 46 countries for testing, as part of the International Meloidogyne project, resulting in many more field trials on a range of crops in many soil types and climates. Field trials, glasshouse trials and in vitro testing of P. lilacinus continues and more isolates have been collected from soil, nematodes and occasionally from insects. Isolates vary in their pathogenicity to plant-parasitic nematodes. Some isolates are aggressive parasites while other, though morphologically indistinguishable, are less or non-pathogenic. Sometimes isolates which looked promising in vitro or in glasshouse trials have failed to provide control in the field.
Many enzymes produced by P. lilacinus have been studied. A basic serine protease with biological activity against Meloidogyne hapla eggs has been identified. One strain of P. lilacinus has been shown to produce proteases and a chitinase, enzymes that could weaken a nematode egg shell so as to enable a narrow infection peg to push through.
Before infecting a nematode egg, P. lilacinus flattens against the egg surface and becomes closely appressed to it. P. lilacinus produces simple appressoria anywhere on the nematode egg shell either after a few hyphae grow along the egg surface, or after a network of hyphae form on the egg. The presence of appressoria appears to indicate that the egg is, or is about to be, infected. In either case, the appressorium appears the same, as a simple swelling at the end of a hypha, closely appressed to the eggshell. Adhesion between the appressorium and nematode egg surface must be strong enough to withstand the opposing force produced by the extending tip of a penetration hypha. When the hypha has penetrated the egg, it rapidly destroys the juvenile within, before growing out of the now empty egg shell to produce conidiophores and to grow towards adjacent eggs.
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I don't understand why this page still exists. I thought the purpose of EOL was to provide a page of information on each species. Having two pages on the same organism, even if it is under different names, creates confusion, especially if the information is not exactly the same. I think you should choose to accept or reject the new name, i.e. Purpureocillium lilacinum, and then delete the other page.