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United States Department of Agriculture

Agricultural Research Service

Title: Managing Resistance for Western Corn Rootworms Using Seed Mixtures of Transgenic Corn Expressing the Cry3b Protein

item French, Bryan
item Chandler, Laurence
item Beck, David
item Vaughn, Ty - MONSANTO CORP
item Pershing, Jay - MONSANTO CORP

Submitted to: Entomological Society of America Regional Meetings
Publication Type: Abstract Only
Publication Acceptance Date: March 2, 2002
Publication Date: N/A

Technical Abstract: Using mixtures of transgenic (Cry3B from Bacillus thuringiensis) and non-transgenic maize seed may become a dependable plan for managing the evolution of corn rootworm (CRW) resistance. To inhibit resistance and allow growers to obtain the maximum benefit of this technology, we investigated the feasibility of a resistance management program using in-field seed mixes (transgenic and non-transgenic) in combination with a new CRW seed treatment. A fundamental assumption is at the appropriate rate, the seed treatment will allow adequate survival of susceptible CRW in the field to prevent or slow the evolutionary rate of resistance and still avoid measurable yield reduction and stalk lodging. We used a factorial design with 5 levels of seed mixtures (100:0 transgenic:non-transgenic, 90:10, 80:20, 60:40, and 0:100), 2 levels of rootworm egg infestation (500/30 cm row and 1000/30 cm row), and 2 levels of seed treatment (designated A and B). Four additional treatments acted as controls. We replicated all treatments 4 times totaling 96 plots. Each plot consisted of 2 rows, 6.2 m in length. Each seed was hand planted on 18 cm spacing. We ensured the proper ratio was planted (e.g. in the 80:20 plots, every 5th seed was non-transgenic). Emergence cages were placed over the maize. Each cage covered 5 plants, representing their respective ratio (e.g. in the 80:20 plots, 4 transgenic and 1 non-transgenic plants were covered). Root ratings were obtained near the end of adult emergence. The results of these data are discussed in terms of managing the resistance of corn rootworms.

Last Modified: 4/22/2015