Prospecting in established cereal cropping ecosystems for microbial enemies of root lesion nematodes

Root lesion nematodes (Pratylenchus spp.) are responsible for millions of dollars in losses to the Australian grains industry each year. Current management strategies are not always practical, so development of alternative control measures would be of significant benefit. Microbial-based pesticides are one such alternative undergoing a revival of interest. The aim of this study was to isolate selected microbial enemies of plant parasitic nematodes, and evaluate their potential to control root lesion nematodes. Twenty-one farms across the Riverina, a district with a long cereal cropping history and known presence of
Pratylenchus spp., were sampled. Three hundred and thirty one (331) isolates of Paecilomyces, Trichoderma, Verticillium and Bacillus were obtained following selective culturing, with Trichoderma being the most abundant. From these isolates, forty six (46) Paecilomyces, twelve (12) Verticillium, seven (7) Trichoderma, and ten (10) Bacillus, plus 13 additional Bacillus isolates from the Charles Sturt University Plant Pathology collection, were selected for assay against Pratylenchus thornei in a greenhouse pot experiment. Seventy one (71) treatments were able to reduce the population number of nematodes
compared to the untreated control, with a number of Paecilomyces isolates providing significant levels of control. Overall, our findings suggest that isolates obtained from established Pratylenchus-containing ecosystems are suitable for investigation as biocontrol agents.