|Jagdale, G - OSU|
|Somasekhar, N - OSU|
|Grewal, P - OSU|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 2001
Publication Date: N/A
Interpretive Summary: Plant-parasitic nematodes cause significant damage to a wide variety of plants throughout the world. Chemical nematicides are the most widely used means of combating these pests, but removal of effective products from the world market and increasing awareness of environmental and human health concerns have created a need for safe alternatives. Several experiments in greenhouses and on turf in the field have shown that entomopathogenic nematodes have the potential to suppress plant- athogenic nematodes. We found that applications of entomopathogenic nematodes to boxwood plants in an arboretum were as effective in reducing populations of several genera of plant-parasitic nematodes as was a chemical nematicide. However, in contrast to the chemical, entomopathogenic nematodes had no effect on free living nematodes in the soil environment. In addition, we demonstrated that living and dead entomopathogenic nematodes were equally effective in suppressing plant- arasitic nematodes. These results help scientists to better understand the interactions between these two diverse groups of nematodes. Nursery managers and homeowners are closer to having environmentally friendly tools in their constant battle against plant-parasites.
Technical Abstract: Effects of live and dead infective juveniles (IJs) of the entomopatogenic nematode (EPN) Steinernema carpocapsae on nematodes associated with boxwood, Buxus spp., were evaluated in 1999 and 2000 field experiments. Living and dead IJs were equally effective, causing more than 50% reductions in populations of plant-parasitic nematodes 15 and 30 days after treatment (dat) both years. There were no differences in reductions of plant-parasitic nematodes following EPN or the chemical nematicide (ethoprop) treatments. In 2000, Criconemella, Hoplolaimus, Longidorus and Rotylenchus were reduced in all treatments 30 dat. In 1999, those genera were unaffected by the treatments, but plant- arasitic nematode populations were decreased. Tylenchorynchus were significantly reduced in all treatments 30 dat in 1999. Further, the 1999 population of Tylenchus was reduced by ethoprop and dead S. carpocapsae 15 dat, while the population of Aphelenchoides was unaffected. Live S. carpocapsae showed no significant effect on either genera. No visible symbiotic bacteria were observed in the dead EPNs used, indicating that dead EPNs, or dead EPNs in combination with dead bacteria, produced the suppressive effect. In contrast to plant- arasitic nematodes, non-stylet bearing nematodes were not affected by f EPNs. Although ethoprop reduced those nematodes 15 dat in 2000, no significant differences were observed 30 dat. These findings suggest allelochemicals from dead or live EPNs and/or their symbiotic bacteria may be selectively acting against plant-parasitic nematodes. Results demonstrate that both live and dead IJs of S. carpocapsae may provide a control strategy for plant-parasitic nematodes on boxwood.