Four populations of Meloidogyne incognita were tested on 57 species of plants from temperate and tropical regions. Juveniles of one or more populations invaded, and induced galls on almost all plants. Except for the population from the West Indies which induced most galls on Nicotiana spp., there was no obvious relationship between the origins of populations and their ability to induce galls on plants from particular regions. Although most plants were hosts for all four populations, many produced only a few galls/egg masses with some of the populations. The differences in galling between populations, and the interaction with plant species were both significant (P < 0.001). Poor hosts often contained fewer juveniles and the rate of juvenile development was often decreased compared with good hosts. Solanum nigrum was an exception in that it was invaded by fewer juveniles than susceptible tomato, but rates of development were similar. The effect of host status differences in four plant species on damage by M. incognita was investigated but only the growth of susceptible tomato was decreased. The growth of the non-host Urtica dioica, of the poor host Datura metal, and of an intermediate host S. nigrum, was unaffected. Unterschiede im Wirtsstatus und ihre Bedeutung fur den durch Meloidogyne incognita verursachten Schaden - Vier Populationen von Meloidogyne incognita wurden an 57 Pflanzenarten aus gemassigten und tropischen Gebieten gepruft. Juvenile einer oder mehrerer Populationen wanderten in fast alle Pflanzen ein und induzierten Gallen. Mit Ausnahme der Population von den Westindischen Inseln, die an Nicotiana spp. die meisten Gallen induzierte, bestand keine deutliche Beziehung zwischen der Herkunft der Populationen und ihrer Fahigkeit, an Pflanzen bestimmter Gebiete Gallbildung zu induzieren. Obwohl die meisten Pflanzen Wirte fur alle vier Populationen waren, bildeten viele von ihnen mit einigen Populationen nur wenige Gallen/Eimassen. Die Unterschiede zwischen den Populationen in Bezug auf Gallbildung und auf Wechselwirkungen mit den Pflanzen waren beide significant (P < 0.001). Schlechte Wirte enthielten oft weniger Juvenile als gute Wirte, und die Entwicklungsrate der Juvenilen war oft vermindert im Vergleich zu guten Wirten. Solanum nigrum bildete insofern eine Ausnahme, als weniger Juvenile eindrangen als in anfallige Tomaten, die Entwicklungsraten aber ahnlich waren. Die Wirkung der Unterschiede im Wirtsstatus auf die Schadigung durch M. incognita wurde an vier Pflanzenarten untersucht. Nur das Wachstum von anfalligen Tomaten wurde vermindert. Das Wachstum des Nichtwirtes Urtica dioica, des schlechten Wirtes Datura metal und des massig guten Wirtes S. nigrum wurde nicht beeinflusst.

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Aim of study: The aim of the study was to isolate the fungi associated with root-knot nematodes and to determine their effect on its eggs hatching in the Green Mountain region of Libya. Material and methods: Soil samples infected with root-knot nematode were collected from the some farms of the Green Mountain region in Libya. Sample collection was carried out during May 2007 within ten different areas. Two fields planted with tomato plants were chosen from the each area. Different types of culture media were used to isolate the fungus species. Fifteen fungi were isolated from the rhizosphere of infected plants. Then, the effect of some isolated and identified fungi on the rate of hatching of nematode eggs was tested. Main results: Isolation results indicate that some of the isolated fungi were considered as parasites on the nematodes. In the study area, Arthrobotrys sp. had the highest percentage of occurrence (70%) and the least one was Penicillium sp. (12.25%). Three inoculum levels of 0.75, 1.5, 2×106 fungal propagules were tested and the highest hatching inhibition (90.5%) was recorded in Paecilomyces lilacinus and the lowest inhibition level (58.4%) was observed in Vertecillium chlamydosporium. Research highlights: As a result of this study, more successful outcomes can be obtained during the biological control of root-knot nematodes.