Gassmann Research Is Strong Reminder of Need for Comprehensive IPM


On July 29, Dr. Aaron Gassmann, an entomologist at Iowa State University, published a paper in the online journal PloS ONE entitled “Field-evolved Resistance to Bt Maize by Western Corn Rootworm.” In his study, Dr. Gassmann reports western corn rootworm (WCR) in four fields in Iowa have developed resistance to the single Bt protein Cry3Bb1 – used in Monsanto YieldGard® VT Triple and Genuity® VT Triple PRO corn products.  

Both of these products continue to perform very well for growers in 2011, providing the expected level of WCR control on more than 99% of the acres planted with this technology.  However, we take performance and efficacy of our products seriously, and we are collaborating with Dr. Gassmann to better understand his initial data and to determine if and how they impact our IPM recommendations to growers. It appears he has demonstrated a difference in survival in the lab, but it is too early to tell whether there are implications for growers in the field.

Since launching a product with this trait in 2003, we have monitored and studied a consistently low incidence of performance issues in limited areas with high WCR densities and under specific environmental conditions.  There has been no measurable increase in the frequency of these performance issues over time.  Ongoing studies with Dr. Gassmann and others are critical to understanding the factors that lead to these performance challenges. The studies will help us further refine local agronomic recommendations and identify other crop protection products that offer growers the best options to manage corn pests and improve overall corn production.  

From agronomic recommendations to innovative trait combinations to a robust discovery platform, we are taking a comprehensive approach to the stewardship of insect-protected traits. 

1.       First launched in 2010, the portfolio of Genuity® SmartStax™ multi-trait corn hybrids continues to grow, providing dual modes of action and increased protection for growers – especially in those areas with increased WCR pressure. 

2.       Through the expansion of Refuge-in-the-Bag (RIB) products such as Genuity® SmartStax™ RIB Complete, farmers are able to more easily ensure refuge compliance.

3.       Researchers continue to discover and develop unique genes in our pipeline that offer farmers new hybrid options with additional modes of action. 

4.       We continue to gather and assess the most current scientific knowledge to develop effective, comprehensive IPM recommendations that strike a balance with grower practicality, acceptance and implementation of the plan. 


Editor’s Note:  Since this statement published in July 2011, we have posted additional resources and information for growers.  For the most current resources, please refer our Corn Rootworm Backgrounder, Insect Resistance Management page, and the 2012 IRM Grower Guide.  Information on our corn rootworm traits and performance can be found in the Monsanto blog:  Looking Ahead to the 2012 Corn Planting Season (January 27, 2012) and Strategies to Ensure Farmer Productivity with Corn Rootworm Control (November 11, 2011).