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Research Project: Genetics and Genomics of Complex Traits in Grain Crops

Location: Plant Genetics Research

Title: A new artificial diet for western corn rootworm larvae is compatible with and detects resistance to all current Bt toxins

Author
item Ludwick, Dalton - University Of Missouri
item Meihls, Lisa
item Huynh, Man - University Of Missouri
item Pereira, Adriano
item French, Bryan
item Coudron, Thomas
item Hibbard, Bruce

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2018
Publication Date: 3/29/2018
Citation: Ludwick, D.C., Meihls, L.N., Huynh, M.P., Pereira, A.E., French, B.W., Coudron, T.A., Hibbard, B.E. 2018. A new artificial diet for western corn rootworm larvae is compatible with and detects resistance to all current Bt toxins. Scientific Reports. 8:5379. https://doi.org/10.1038/s41598-018-23738-z.

Interpretive Summary: Insect resistance to transgenic crops is a growing concern for farmers, regulatory agencies, the seed industry, and researchers alike for a number of pests including the western corn rootworm. Instances of field-evolved resistance have been documented to each of the four transgenic toxins available to manage the western corn rootworm. To characterize resistance, western corn rootworm populations causing unexpected damage to transgenic corn are evaluated in plant and/or diet assays. Past issues with diet toxicity assays involving western corn rootworm larvae included diet contamination, insufficient diet nutrition, and the inability to make direct comparisons of data from different Bt proteins due to differing proprietary artificial diets. Our group has generated a new, publicly available diet with improved nutrition for western corn rootworm larvae. For the current manuscript, we tested the compatibility of all four Bt proteins currently marketed for the control of western corn rootworm on our diet and specific proprietary diets corresponding to each toxin using a susceptible colony of western corn rootworm. We also tested western corn rootworm colonies selected for resistance to each protein to assess the ability of the diet toxicity assay to detect Bt resistance. Our diet is compatible with each of the proteins and can differentiate resistant colonies from susceptible colonies for each protein. Moving forward, our diet will allow researchers to monitor resistance without the nutritional differences present between multiple diets.

Technical Abstract: Insect resistance to transgenic crops expressing one or more genes from Bacillus thuringiensis Berliner (Bt) is a growing concern for farmers, regulatory agencies, the seed industry, and researchers alike. Western corn rootworm (Diabrotica virgifera virgifera LeConte) is a pest of corn (Zea mays L.) in Europe and North America. Since 2009, instances of field-evolved Bt resistance or cross resistance have been documented in the refereed literature for each of the four Bt proteins meant to control western corn rootworm. To characterize resistance, western corn rootworm populations causing unexpected damage to Bt corn are evaluated in plant and/or diet toxicity assays. Issues with diet toxicity assays involving western corn rootworm larvae include diet contamination, insufficient diet nutrition, and the inability to make direct comparisons of data from different Bt proteins due to differing proprietary artificial diets. Our group has generated a new, publicly available diet (WCR-MO1) with improved nutrition for western corn rootworm larvae. For the current manuscript, we tested the compatibility of all four Bt proteins currently marketed for the control of western corn rootworm on our diet and specific proprietary diets corresponding to each toxin using a susceptible colony of western corn rootworm. We also tested western corn rootworm colonies selected for resistance to each protein to assess the ability of the diet toxicity assay to detect Bt resistance. The WCR-MO1 diet is compatible with each of the proteins and can differentiate resistant colonies from susceptible colonies for each protein. Our diet will allow researchers to monitor resistance without the confounding nutritional differences present between multiple diets.