Propagation and feeding behavior of the mycetophagous nematode, Aphelenchus avenue, on four species of soil fungi

Three isolates of the mycetophagous nematode Aphelenchus avenae collected in Kyushu, Japan, were investigated at 25°C for their propagation and feeding behavior on the hyphae of Rhizoctonia solani (Rs), Botrytis cinerea (Bc), Fusarium oxysporum (Fo), and Verticillium dahliae (Vd). There were large differences in the population growth between the nematode isolates. On 30 days after inoculation with three individuals of 4th-stage juveniles onto the fungi growing on the 1/5 strength PDA medium in a Petri dish (9-cm diam.), the nematode population size was in the range of 21, 000-63, 000 for Bc and Rs, and 1, 000-10, 000 for Vd and Fo. Taking the hyphal diameter of Rs for 1.0, the ratio was almost the same, 0.2, and 0.4 for Bc, Vd, and Fo, respectively. Video-assisted analyses of nematode feeding behavior showed that the nematodes were more preferably attracted to Fo than to the other three fungus species. The frequencies of stylet thrusting per 10 min were 5-12 times for Rs and Bc, and 20-106 times for Fo or Vd. The duration of a single stylet stabbing was 4-9 sec for Rs and Bc, while it was 1-2 sec for Fo and Vd. The pulsation frequencies of median valve per a single feeding were 5-10 pulse for Rs and Bc, and 0.5-1.0 pulse for Fo and Vd. The lower nematode reproduction on Fo and Vd was possibly due to the thinner width of these hyphae than the length of nematode stylet (ca. 8μm). There is no extracorporeal digestion in these three nematode isolates tested. Jpn. J. Nematol. 35 (1), 13-19 (2005).