Reserves
Combating Resistance
Concern over the resistance of rootworm to the Bt toxin led to the application of refuges of non-Bt maize. These refuges were planted as breeding grounds for rootworms to spread their Bt susceptible genes and delay the resistance to the Bt toxin (Gassmann, 2012). Refuges allow for the growth of populations that have not been exposed to the Bt toxin and thereby not selected for Bt resistance (Gassmann, 2012). The populations of rootworms in these refuges then breed with populations that have been exposed to Bt toxin and, therefore, selected for Bt resistance (Gassmann, 2012). When these two populations bred they slightly relieve the prominence of Bt resistant genes in their offspring (Gassmann, 2012). This does not solve the issue of resistance but rather pushes it back to later generation of rootworms (Gassmann, 2012).
Increasing Necessary Reserves
But even with refuge sizes of 5-20%, resistance occurred eight years earlier than predicted (Gassmann, 2012). Since that paper was published, the Environmental Protection Agency now requires refuges of 20% non-GMO corn be planted by farmers as a remedial plan for rootworm adaption to Bt toxin (Tabashnik & Gould, 2012). However, Tabashnik and Gould argue that this is too little too late: the EPA should try to head off resistance instead of trying to fix it by following the “SAP recommended [a] 50% refuge” of non-Bt toxin producing corn (2012). It is clear that with a necessary refuge of 50% non-GMO corn to counteract the negative ecological affect of Bt corn this technology of using bacteria DNA in corn is not effective or, at the very least, loosing its effectiveness (Tabashnik & Gould, 2012).
Concern over the resistance of rootworm to the Bt toxin led to the application of refuges of non-Bt maize. These refuges were planted as breeding grounds for rootworms to spread their Bt susceptible genes and delay the resistance to the Bt toxin (Gassmann, 2012). Refuges allow for the growth of populations that have not been exposed to the Bt toxin and thereby not selected for Bt resistance (Gassmann, 2012). The populations of rootworms in these refuges then breed with populations that have been exposed to Bt toxin and, therefore, selected for Bt resistance (Gassmann, 2012). When these two populations bred they slightly relieve the prominence of Bt resistant genes in their offspring (Gassmann, 2012). This does not solve the issue of resistance but rather pushes it back to later generation of rootworms (Gassmann, 2012).
Increasing Necessary Reserves
But even with refuge sizes of 5-20%, resistance occurred eight years earlier than predicted (Gassmann, 2012). Since that paper was published, the Environmental Protection Agency now requires refuges of 20% non-GMO corn be planted by farmers as a remedial plan for rootworm adaption to Bt toxin (Tabashnik & Gould, 2012). However, Tabashnik and Gould argue that this is too little too late: the EPA should try to head off resistance instead of trying to fix it by following the “SAP recommended [a] 50% refuge” of non-Bt toxin producing corn (2012). It is clear that with a necessary refuge of 50% non-GMO corn to counteract the negative ecological affect of Bt corn this technology of using bacteria DNA in corn is not effective or, at the very least, loosing its effectiveness (Tabashnik & Gould, 2012).
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