Six species of entomopathogenic nematodes and a fungivorous nematode, Aphelenchus avenae, were tested for their effects on root invasion of Meloidogyne incognita and Pratylenchus coffeae. The beneficial nematodes were applied before, at the same time, or after the inoculation of plant nematodes onto Agrobacterium-transformed cucumber hairy roots in a petri dish or onto seedlings in pots. All beneficial nematodes tested were more or less suppressive to root invasion by plant nematodes. In particular, both Steinernema carpocapsae and A. avenae reduced the root invasion by 97% on agar plate with 1×10⁴ mematodes and 76% in sterilized soil with 1× 10⁶ dose level. Steinernema sp. from Malaysia, S. anomali, S. glaseri, Heterorhabditis bacteriophora, and A. avenae were most effective following simultaneous application with plant nematodes. These were mostly cruiser-type nematodes, whereas S. carpocapsae and S. kushidai, typical ambusher-type foragers, gave the best results by preapplication. Pratylenchus coffeae was generally more susceptible to other nematodes than M. incognita. In nonautoclaved soil, the effect of beneficial nematodes was not so marked as in autoclaved soil. Jan. J. Nematol. 26 (1/2): 1-11 (1996).

View full abstract

Life cycle studies of Ditylenchus angustus demonstrated that one generation time from egg to egg took 8 days on one-week-old rice seedling at 24-26°C. The eggs were laid at 2-celled stage and embryos hatched in sterile water 64-66 hr after the egglaying. The duration of J2, J3 and J4 was 1, 1 and 2 days, respectively. Females started the egg-laying 1 day after the adulthood. Fecundity of D. angustus on rice plant was always higher than on the fungus, Botrytis cinerea. Fecundity declined on both hosts following the pre-culture on the fungi for 1 month (1MF) or for 6 months (6MF) prior to inoculation. D. angustus increased 1067, 993 and 734-fold on rice plant 40 days after inoculation with 20 adults (10 females and 10 males) collected from rice plant, 1MF and 6MF, respectively. On B. cinerea after the same period from the same initial population the multiplications were 291 and 229-fold, from the inoculum from rice plant and 6MF, respectively. Jpn. J. Nematol. 26 (1/2) 12-22 (1996).

View full abstract

The entomopathogenic nematode, Steinernema kushidai, is expected to be used as a biological control agent against insect pests inhabiting in soil, especially white grubs (8, 9, 10). This nematode is accompanied by a symbiotic bacterium identified as Xenorhabudus japonicus (11). Symbiotic bacteria associated with the genera Steinernema and Heterorhabditis are demonstrated to play important roles in killing their host insects and also in propagation of nematodes (1). Therefore, bioassay using axenic S. kushidai may be useful to analyze the efficacious pathogenicity of S. kushidai against white grubs.
Since GLASER (6) first brought S. glaseri into axenic culture, many improvements on media and techniques of axenic culture of entomopathogenic and free-living nematodes have been made (5). In the present study, the effect of “transferring” on axenic culture of S. kushidai was studied by comparing propagation of infective juveniles (IJs) treated by three different transferring methods, and this is reported here.

View full abstract

Recently enzyme phenotypes, especially those of esterase have been demonstrated to be species-specific for Meloidogyne and useful taxonomic characters to identify the species of this genus (1, 2, 3, 4, 5). In Japan NARABU et al.(4) first reported that three major species of root-knot nematodes including Meloidogyne hapla, M. incognita and M. javanica could be identified based on enzyme phenotypes of esterase and other five enzymes. In this paper we show the esterase phenotypes of three populations of Meloidogyne species, which were idetified as M. javanica by morphological character of perineal patterns, from Chiba, Kanagawa and Fukushima Prefectures.

View full abstract