Host and temperature preference, male occurrence and morphometrics of fungivorous nematode, Aphelenchus avenae isolates from Japan

摘要

Host and temperature preference, male occurrence, and morphometrics of 39 isolates of Aphelenchus avenae were investigated. Of the 39 isolates, 33 were from 7 districts of Kyushu, 3 from Okinawa, and 2 from Ibaraki and 1 from Fukushima prefecture of Honshu. The host preferences were investigated on 4 species of fungi; Botrytis cinerea, Rhizoctonia solani AG-4, Fusarium oxysporum f. sp. melonis, and Pythium aphanidermatum growing on 1/5 strength PDA medium. The nematodes were incubated on respective fungus mat for 30 days at 25 and 30 deg C. Host fungi and temperatures gave rise to various levels of reproduction and male occurrence. The isolates were divided into 5 groups based on their reproductivity on their host fungi at the 2 temperature regimes. Most of the isolates of A. avenae propagated themselves at 25 deg C on B. cinerea and R. solani AG-4, whereas some isolates, especially from Okinawa and Kagoshima i.e. southern parts of Kyushu, preferred 30 deg C. The highest multiplication from the initial 10 females at 25 deg C, 30 days after inoculation on B. cinerea was 60,850 given by Nagasaki isolate (NA3). The maximum multiplication 48,420 at 30 deg C occurred on R. solani by Kagoshima isolate (KA3). The occurrence of males was very low in all isolates and it occurred only at 30 deg C. De MAN's value of body dimension were measured and showed no significant variations among the isolates. Besides, there were no relations between groupings by host preference and by body dimension.