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Title: Response of maize hybrids with and without rootworm-and drought-tolerance to rootworm infestation under well-watered and drought conditions

Author
item MAHMOUD, MERVAT - University Of Missouri
item SHARP, ROBERT - University Of Missouri
item Oliver, Melvin
item FINKE, DEBBIE - University Of Missouri
item BOHN, M - University Of Illinois
item ELLERSIECK, MARK - University Of Missouri
item Hibbard, Bruce

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2017
Publication Date: 2/10/2018
Publication URL: http://handle.nal.usda.gov/10113/5922791
Citation: Mahmoud, M.A., Sharp, R.E., Oliver, M.J., Finke, D.L., Bohn, M., Ellersieck, M.R., Hibbard, B.E. 2018. Response of maize hybrids with and without rootworm-and drought-tolerance to rootworm infestation under well-watered and drought conditions. Journal of Economic Entomology. 111(1): 193-208. https://doi.org/10.1093/jee/tox309.

Interpretive Summary: Both water deficit and western corn rootworm can substantially affect maize yield. Previous anecdotal evidence in the field had suggested that when both plant stress factors were present, the effect on maize was greater than would be expected from the combined effects of the two factors alone. Field studies were conducted in 2012, 2013, and 2014 with varying soil moisture levels, western corn rootworm infestation levels, and maize hybrids (with and without tolerance to drought and rootworm feeding). In 2012 and 2013, western corn rootworm infestation significantly impacted yield, but its impact on yield was much less than the effect of drought. The amount of feeding damage caused by the western corn rootworm was not significantly impacted by drought or its interactions with western corn rootworm infestation in any year. Both drought and western corn rootworm affected a series of plant response factors related to drought stress, and the magnitude of the effect of drought versus western corn rootworm infestation level varied depending on which plant response was being evaluated. In general, drought had a greater effect on maize growth factors than did rootworm. A greater understanding of the effects of plant stress factors on maize growth will allow better decisions by growers as they attempt to optimize yield.

Technical Abstract: Anecdotal data have suggested that the effect of the western corn rootworm, Diabrotica virgifera virgifera LeConte, is greater under drought and the effect of drought is greater under rootworm infestations, but few experiments have controlled both moisture and rootworm levels. Field studies were conducted in 2012, 2013, and 2014 with treatments in a factorial arrangement varying soil moisture levels, western corn rootworm infestation levels, and maize hybrids (with and without tolerance to drought and rootworm pressure). In 2012 and 2013, western corn rootworm infestation significantly impacted yield, but its impact on yield was much less than the effect of drought. When under drought and rootworm pressure, the hybrid with Cry34/35Ab1 + Pioneer’s AQUAmax trait (tolerance to both western corn rootworm and drought) was generally higher yielding and significantly less water-stressed than other hybrids. Root damage ratings were not significantly impacted by drought or its interactions with western corn rootworm infestation. Both drought and western corn rootworm affected water potential, stomatal conductance, root complexity, and western corn rootworm beetle emergence. The magnitude of the effect of drought versus western corn rootworm infestation level varied depending on the factor being evaluated, but in general drought had a greater effect on maize growth factors.