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Ontario Grain Farmer Magazine

Understanding and managing the relationship between insect damage and mycotoxin accumulation in grain corn

Principal Investigators: Art Schaafsma and Jocelyn Smith

Research Institution: University of Guelph (U of G)

Timeline: May 2012 – February 2015

Objectives:

  • Determine the relationship between insect feeding damage to corn ears, Gibberella ear rot infection and mycotoxin accumulation in grain corn.
  • Determine the relationship between insect feeding damage to corn ears and mycotoxin accumulation in grain corn under various pest management regimes.
  • Determine the most effective applied field management strategies for control of ear-feeding insects, Gibberella ear rot and mycotoxin accumulation in grain corn.

Impacts:

  • The incidence of WBC feeding injury can result in increased DON concentration in grain corn, regardless of the extent of injury.
  • Of the Bt corn products, only Vip3A hybrids reduce WBC feeding injury. WBC in Ontario are resistant to Cry1F. Application of an insecticide/fungicide tank mix at full silking (R1) is the most efficient approach for prevention of deoxynivalenol contamination for non-Vip hybrids in the presence of WBC infestation.
  • In the presence of western bean cutworm, a strategic approach including Vip3A corn hybrids, fungicides, and insecticides is required to manage the corn pest complex including WBC and Fusarium graminearum (Gibberella ear rot).

Scientific Summary:

Corn (Zea mays L.) crops in Ontario frequently sustain grain quality losses due to mycotoxin contamination resulting from Gibberella ear rot (GER), Fusarium graminearum Schwabe (Teleomorph, Gibberella zeae Schw. Petch). Western bean cutworm (Striacosta albicosta (Smith) Lepidoptera: Noctuidae) (WBC) has recently expanded its range into Ontario. Recently, an increase in the occurrence of deoxynivalenol (DON) and fumonisins (FB) mycotoxins in corn resulting from F. graminearum and F. verticillioides infection has been observed related to kernel damage caused by WBC injury. Mycotoxins cause acute and chronic deleterious effects to humans and livestock when consumed; therefore ear mould incidence poses a serious threat to domestic and export grain markets. The relationship between injury by WBC, Fusarium infection and mycotoxin contamination in corn is not known; however, numerous studies have shown that insect injury may contribute to development of fungal diseases in grain by providing supplemental entry points for infection.

The goal of this research was 1) to determine the contribution of WBC feeding injury to overall mycotoxin accumulation in corn hybrids, 2) to evaluate the effectiveness of commercially available Bt-corn events in combination with insecticide and fungicide applications to control WBC injury, GER, and mycotoxin contamination, and 3) to determine effective management strategies for Ontario corn producers. Small plot and commercial scale field trials were conducted in Ontario from 2012-14 under natural and artificial WBC and disease infestations.

The incidence of WBC feeding injury and GER were found to increase the concentration of DON in grain corn under environmental conditions favourable for F. graminearum infection. The incidence or presence of WBC injury was found to be more important for DON accumulation than was the severity or extent of feeding injury. In field experiments that were naturally infested with WBC, significantly less kernel damage due to WBC feeding was observed in hybrids expressing Vip3A insecticide protein than in non-Bt and Cry1F-expressing hybrids. Cry1F did not provide better protection from insect injury than non-Bt hybrids. Practical resistance to Cry1F by WBC in Ontario was documented during the time of this project.

For corn hybrids lacking Vip3A expression, application of pyrethroid or diamide insecticides was effective in reducing the severity of kernel damage compared to the non-treated control when applied at either the VT or R1 stage; no difference in efficacy was measured between Voliam Xpress (lambda-cyhalothrin + chlorantraniliprole) or Coragen (chlorantraniliprole). In the presence of WBC infestation, fungicide application alone did not reduce DON; however, the combination of Voliam Xpress + Proline applied simultaneously at R1, or separately at VT and R1, respectively, significantly reduced the accumulation of DON compared to the non-treated control.

External Funding Partners: Pioneer Hi-Bred International Ltd., Syngenta Crop Protection Canada Inc., Bayer Crop Sciences Inc.

Canadian Agricultural Adaptation Program (CAAP). Investment in this project was provided by AAFC through the CAAP. In Ontario, this program was delivered by the Agricultural Adaptation Council.

Project Related Scientific and Popular Publications:

Scientific Publications:

Smith, J.L., C.D. DiFonzo, T.S. Baute, A.P. Michel, and C.H. Krupke. (2019) Ecology and management of the western bean cutworm (Lepidoptera: Noctuidae) in corn and dry beans – Revision with focus on the Great Lakes region. Journal of Integrated Pest Management. 10(1): 27. doi.org/10.1093/jipm/pmz025.

Smith, J.L., Limay-Rios, V., Hooker, D.C., and Schaafsma, A.W. (2018) Fusarium graminearum mycotoxins in maize associated with Striacosta albicosta (Lepidoptera: Noctuidae) injury. Journal of Economic Entomology 111(3): 1227-1242. doi.org/10.1093/jee/toy005.

Smith, J.L., Lepping, M. D., Rule, D. M., Farhan, Y., and Schaafsma, A.W. (2017) Evidence for field-evolved resistance of Striacosta albicosta (Lepidoptera: Noctuidae) to Cry1F Bacillus thuringiensis protein and transgenic corn hybrids in Ontario, Canada. Journal of Economic Entomology 110(5): 2217-2228. doi: 10.1093/jee/tox228.

Extension Publications:

Baute, T., Schaafsma, A., and Smith, J. (2017) WBC 101: ID and Control. Scouting and management in field corn. Ontario Grain Farmer. June/July 2017. Pp 30-32.

Baute, T., Smith, J., and Schaafsma, A. (2017) Western bean cutworm. Scouting and management in field corn. Bulletin. http://fieldcropnews.com/wp-content/uploads/2017/05/WBC-Scouting-and-Management-2017-Corn-Final.pdf.

Smith, J. (2014) Scout for western bean cutworm and ear mould now. BauteBugBlog. September 22, 2014. http://fieldcropnews.com/2014/09/scout-for-western-bean-cutworm-and-ear-mould-now/.

Smith, J. (2014) Does spraying Bt corn for western bean cutworm make sense? BauteBugBlog. July 7, 2014. http://fieldcropnews.com/2014/07/does-spraying-bt-corn-for-western-bean-cutworm-make-sense/.

DiFonzo, C., Baute, T., Hammond, R., Krupke, C., Michel, A., Schaafsma, A., Shields, E., Smith, J., and Tooker, J. (2013) Consensus recommendation: Managing western corn rootworm resistance to Bt on the fringe. http://msuent.com/assets/pdf/FringeConsensusSAP2013.pdf.

Smith, J. (2013) ALERT – Fields in high risk western bean cutworm regions need to be scouted! BauteBugBlog, September 20, 2013. http://fieldcropnews.com/2013/09/alert-fields-in-high-risk-western-bean-cutworm-regions-need-to-be-scouted/.