Protecting maize from rootworm damage with the combined application of arbuscular mycorrhizal fungi, Pseudomonas bacteria and entomopathogenic nematodes

Authors: JAFFUEL, GEOFFREY - Neuchatel University - Switzerland; IMPERIALI, NICOLA - University Of Lausanne; Shelby, Kent; CAMPOS-HERRERA, RAQUEL - University Of La Rioja; Geisert, Ryan; MAURHOFER, MONIKA - Eth Zurich; LOPER, JOYCE - Oregon State University; KEEL, CHRISTOPH - University Of Lausanne; TURLINGS, TED - Neuchatel University - Switzerland; Hibbard, Bruce

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2019
Publication Date: 2/28/2019
Citation: Jaffuel, G., Imperiali, N., Shelby, K., Campos-Herrera, R., Geisert, R.W., Maurhofer, M., Loper, J.E., Keel, C., Turlings, T.C., Hibbard, B.E. 2019. Protecting maize from rootworm damage with the combined application of arbuscular mycorrhizal fungi, Pseudomonas bacteria and entomopathogenic nematodes. Scientific Reports. 9:3127. https://doi.org/10.1038/s41598-019-39753-7.
DOI: https://doi.org/10.1038/s41598-019-39753-7

Interpretive Summary: Corn rootworm resistance to transgenic crops is a growing concern for farmers, regulatory agencies, the seed industry, and researchers in the U.S. Corn Belt the western corn rootworm has developed resistance to most control tactics used, including the use of insecticides and transgenic corn varieties that express insecticidal toxins. Thus development and evaluation of innovative methods for rootworm control, the application of beneficial soil organisms, was undertaken. We conducted field trials on corn planted in Missouri fields during three consecutive field seasons (2015-2017) using applications of arbuscular mycorrhizal fungi, entomopathogenic bacteria, and entomopathogenic nematodes. We applied the three organisms, alone or in combinations, in plots that were artificially infested with western corn rootworm, and in non-infested control plots. In each field season we measured the effects of the treatments on corn yield, root damage, the incidence of rootworm larvae, and on rootworm larval weight. We observed variable effects of the treatments, but they were always positive for the plants. Both researchers and industry will find these results to be important for the development of nematodes as biological control agents targeting rootworms.

Technical Abstract: Diabrotica virgifera virgifera LeConte, the western corn rootworm (WCR), is the most destructive pest of maize in North America, and has recently spread across much of Europe. Its subterranean larval stages are hard to reach with pesticides and it has evolved resistance to conventional management techniques. The application of beneficial soil organisms is being considered as an alternative. A previous study that combined the application in wheat fields of arbuscular mycorrhizal fungi, entomopathogenic Pseudomonas bacteria, and entomopathogenic nematodes was found to promote growth and protection against a natural pest infestation, without negative cross effects. We hypothesized that the application of these organisms would have similar beneficial effects in WCR-infested maize fields. During three consecutive years (2015-2017), we conducted trials in Missouri (USA) in which we applied the three organisms, alone or in combinations, in plots that were artificially infested with WCR and in non-infested control plots. Each year, we measured the effects of the treatments on maize yield, root damage, the incidence of WCR larvae and on larval weight. We observed variable effects of the treatments, but they were always positive for the plants.