Why are all the Rootworm Trait packages failing at the same time?

• All the Bt-rootworm trait packages are failing across the corn growing region independent of the seed company because all the seed companies are using the same Bt – RW toxins regardless of seed brand.  

• There are only three Bt-RW toxins in the market and functionally, two of those toxins are so similar that rootworm cross resistance to all three related toxins was reported in 2014.

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What are those three Bt-RW toxins?

The initial RW trait packages in corn contained a single toxin when introduced.

• Monsanto/Bayer single toxin (Cry3Bb1) was first marketed in 2003 as YieldGard-RW or YieldGard TriplePro.  Rootworm resistance was documented in 2009.‍

• Dow/Corteva single toxin (Cry34Ab1/Cry35Ab1) was first marketed in 2006 as Herculex-RW or AcreMax.  Rootworm resistance was documented in 2013.

• Syngenta single toxin (mCry3A) was first marketed in 2007 as Agrisure.  Rootworm resistance documented in 2011.

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What are Pyramid trait packages?

When corn seed companies begin seeing rootworm trait failure in the field, they introduced two toxin rootworm trait packages to combat the emerging rootworm resistance to the single toxin trait packages.  These two toxin trait packages were simply two different single RW toxins combined into a single trait package.

• Monsanto/Bayer introduced SmartStax in2010 which is the combination of their RW toxin (Cry 3Bb1) + the Dow/Corteva RW toxin (Cry34Ab1/Cry35Ab1).  Rootworm resistance documented in 2017.‍

• Syngenta introduced Duracade which was introduced in 2014.  Duracade is a combination of two closely related Syngenta toxins (mCry3A + eCry3.1Ab) and Rootworm resistance was documented in 2016.

• Corteva/Pioneer introduced Qrome in 2014.  Qrome is a combination of the Syngenta toxin (mCry3A) and their own Herculex-RW toxin (Cry34Ab1/Cry35Ab1).  Resistance to this pyramid has not been documented in the scientific literature. but resistance to the individual toxins were reported in 2011 and 2013.  Poor field performance of this pyramid is frequently reported.

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What are the newly advertised three RW trait packages?

• Bayer has recently introduced a 3-RW toxin trait package (SmartStax Pro) for corn farmers and a similar 3-RW trait package (Vorceed) is scheduled to be introduced by Corteva/Pioneer in the near future.  Both trait packages by the two different companies contain near identical RW toxins and are functionally identical.  

• In both cases, a new RNAi toxin (dvSf7) has been added to either SmartStax or Qrome.  Research has shown that corn rootworm has developed resistance in the laboratory to the new RNAi toxin in just two generations (equivalent to 2 years) and reported in 2018.