Host status of 10 fungal isolates for two nematode species, Filenchus misellus and Aphelenchus avenae

The classification of nematodes in the family Tylenchidae into plant parasites, plant associates or fungal-feeders for community analyses, have been much discussed by nematode ecologists. For an appropriate classification, fungal-feeding habits in the family need to be studied. To evaluate the host status of 10 fungal isolates for Filenchus misellus (Tylenchidae) and Aphelenchus avenae (Aphelenchida, Aphelenchidae), population growth rates, body length and width and sex ratios of the nematodes were measured after 40-day culture on fungal colonies at 25 °C. For F. misellus, the fungi determined as good hosts were two Basidiomycota fungi (Agaricus bisporus, Coprinus cinereus), three Ascomycota fungi (Chaetomium cochlioides, Chaetomium funicola, Chaetomium globosum) and a plant-pathogenic fungus (Rhizoctonia solani) on the basis of nematode population growth rate and female body length. Interestingly Pleurotus ostreatus, known as a predaceous fungus for the other nematodes, was also a good host for F. misellus. While, for A. avenae, good hosts were four plant-pathogenic fungi (Fusarium oxysporum f. sp. conglutinans, F. oxysporum f. sp. cucumerinum, Pythium ultimum, R. solani) and A. bisporus. A. avenae was trapped and preyed upon by Pleurotus hyphae. In F. misellus, males were 7–21% of adults, but the ratio did not correlate significantly with the population growth rate. In A. avenae, no male occurred. Differences in habitat preference between Filenchus and Aphelenchus were explained on the basis of the host status and habitat preferences of the tested fungi.