Interference by Entomopathogenic and Fungivorous Nematodes of Root Invasion by Plant-parasitic Nematodes

Abstract

Six species of entomopathogenic nematodes Steinernema and Heterorhabditis spp. 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 X 104 nematodes and 76% in sterilized soil with 1 X 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.