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Aaron J. Gassmann - One of the best experts on this subject based on the ideXlab platform.
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Inheritance and Fitness Costs of Cry3Bb1 Resistance in Diapausing Field Strains of Western Corn Rootworm (Coleoptera: Chrysomelidae).
Journal of economic entomology, 2020Co-Authors: Ram B. Shrestha, Aaron J. GassmannAbstract:Field-evolved resistance to Cry3Bb1 Corn by Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Colleoptera: Chrysomellidae), has been reported in field populations in Iowa, Illinois, Nebraska, and Minnesota. Inheritance and fitness costs associated with Cry3Bb1 resistance have been determined for non-diapausing laboratory strains of Western Corn Rootworm with either laboratory-selected resistance or field-derived resistance. However, information on inheritance and fitness costs of Cry3Bb1 resistance in the diapausing field populations is lacking. In this study, we determined the inheritance of Cry3Bb1 resistance for four diapausing field strains of Western Corn Rootworm using plant-based bioassays. We also determined the fitness costs for eight diapausing field populations in a greenhouse experiment. We found that Cry3Bb1 resistance was an autosomal trait and that the inheritance of resistance was mostly non-recessive; however, there was some variation in the dominance of Cry3Bb1 resistance. We did not find evidence of fitness costs affecting survival to adulthood, developmental rate, or adult dry mass. However, we did detect a fitness cost affecting adult size. The results of this study will add to the current understanding of field-evolved resistance to Cry3Bb1 Corn by Western Corn Rootworm and help in developing better strategies to manage resistance.
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field evolved resistance by Western Corn Rootworm to cry34 35ab1 and other bacillus thuringiensis traits in transgenic maize
Pest Management Science, 2020Co-Authors: Aaron J. Gassmann, Ram B. Shrestha, Abigail L Kropf, Coy R. St. Clair, Ben D BrenizerAbstract:Background Transgenic crops producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage agricultural insect pests. However, widespread adoption of Bt crops has led to the evolution of Bt resistance. The Western Corn Rootworm, Diabrotica virgifera virgifera, is among the most serious pests of maize in the midWestern United States and is currently managed with Bt maize. To date, there is evidence of field-evolved resistance to all Bt toxins used to manage this pest. While Western Corn Rootworm resistance to Cry3Bb1, and the closely related mCry3A and eCry3.1Ab traits, is widely distributed within the Midwest, fewer cases of Cry34/35Ab1 resistance have been observed, and planting of Cry34/35Ab1 maize is one of the methods used to manage Cry3-resistant Rootworm. Results We found that fields with high levels of root injury to Cry34/35Ab1 maize by Western Corn Rootworm were associated with Cry34/35Ab1-resistant Western Corn Rootworm. Additionally, a population not associated with high levels of root injury was found to be resistant to Cry34/35Ab1. In all cases, populations that were resistant to Cry34/35Ab1 also were resistant to Cry3 traits. Conclusions Western Corn Rootworm resistance to Cry34/35Ab1 has continued to persist in the agricultural landscape and has likely increased. The presence of Rootworm populations with resistance to all available Bt traits threatens the utility of current and future transgenic technologies to manage this pest. Decreased reliance on Cry34/35Ab1 and better use of integrated pest management will be essential to preserve Bt susceptibility in Western Corn Rootworm. © 2019 Society of Chemical Industry.
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Field-evolved resistance by Western Corn Rootworm to Cry34/35Ab1 and other Bacillus thuringiensis traits in transgenic maize.
Pest management science, 2019Co-Authors: Aaron J. Gassmann, Ram B. Shrestha, Abigail L Kropf, Coy R. St. Clair, Ben D BrenizerAbstract:Background Transgenic crops producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage agricultural insect pests. However, widespread adoption of Bt crops has led to the evolution of Bt resistance. The Western Corn Rootworm, Diabrotica virgifera virgifera, is among the most serious pests of maize in the midWestern United States and is currently managed with Bt maize. To date, there is evidence of field-evolved resistance to all Bt toxins used to manage this pest. While Western Corn Rootworm resistance to Cry3Bb1, and the closely related mCry3A and eCry3.1Ab traits, is widely distributed within the Midwest, fewer cases of Cry34/35Ab1 resistance have been observed, and planting of Cry34/35Ab1 maize is one of the methods used to manage Cry3-resistant Rootworm. Results We found that fields with high levels of root injury to Cry34/35Ab1 maize by Western Corn Rootworm were associated with Cry34/35Ab1-resistant Western Corn Rootworm. Additionally, a population not associated with high levels of root injury was found to be resistant to Cry34/35Ab1. In all cases, populations that were resistant to Cry34/35Ab1 also were resistant to Cry3 traits. Conclusions Western Corn Rootworm resistance to Cry34/35Ab1 has continued to persist in the agricultural landscape and has likely increased. The presence of Rootworm populations with resistance to all available Bt traits threatens the utility of current and future transgenic technologies to manage this pest. Decreased reliance on Cry34/35Ab1 and better use of integrated pest management will be essential to preserve Bt susceptibility in Western Corn Rootworm. © 2019 Society of Chemical Industry.
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Field and Laboratory Studies of Resistance to Bt Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae).
Journal of economic entomology, 2019Co-Authors: Ram B. Shrestha, Aaron J. GassmannAbstract:Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), has developed resistance to transgenic Corn that produces the insecticidal toxin Cry3Bb1 derived from the bacterium Bacillus thuringiensis (Bacillales: Bacillaceae) (Bt), with cross-resistance extending to Corn with Bt toxins mCry3A and eCry3.1Ab. Additionally, some populations of Western Corn Rootworm have evolved resistance to Cry34/35Ab1 Corn. We conducted a 2-yr field and laboratory study that included three field locations: 1) Bt-susceptible population, 2) field with a recent history of Cry3Bb1 resistance, and 3) field with a long-term history of Cry3Bb1 resistance. The population with recently evolved Cry3Bb1 resistance showed resistance to Cry3Bb1 Corn in both laboratory bioassays and field evaluations; by contrast, the population with a long-term history of Cry3Bb1 resistance showed resistance, in both laboratory and field experiments to Cry3Bb1 Corn and Corn with a pyramid of mCry3A plus eCry3.1Ab Corn. Field-based evaluations also showed that the field population with a long-term history of Cry3Bb1 resistance imposed higher root injury to Cry3Bb1 Corn and the pyramid of mCry3A plus eCry3.1Ab compared with the susceptible control. The results of this study are discussed in the context of developing strategies to manage Western Corn Rootworm in areas where populations have evolved resistance to Cry3Bb1 Corn.
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Mean female longevity and egg number of control and tested female Western Corn Rootworm from forced flight experiments (Mean ± SE).
2019Co-Authors: Aaron J. Gassmann, Thomas W. SappingtonAbstract:Mean female longevity and egg number of control and tested female Western Corn Rootworm from forced flight experiments (Mean ± SE).
Bruce E Hibbard - One of the best experts on this subject based on the ideXlab platform.
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Detection of alternative splicing in Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) in association with Bt resistance using RNA-seq and PacBio Iso-Seq
2020Co-Authors: Z. Zhao, Bruce E Hibbard, Christine G. Elsik, Kent S. ShelbyAbstract:BackgroundAlternative splicing is one of the major mechanisms that increases transcriptome diversity in eukaryotes, including insect species that have gained resistance to pesticides and Bt toxins. In Western Corn Rootworm (Diabrotica virgifera virgifera LeConte), neither alternative splicing nor its role in resistance to Bt toxins has been studied. ResultsTo investigate the mechanisms of Bt resistance we carried out single-molecule real-time (SMRT) transcript sequencing and Iso-seq analysis on resistant, eCry3.1Ab-selected and susceptible, unselected, Western Corn Rootworm neonate midguts which fed on seedling maize with and without eCry3.1Ab for 12 and 24 hours. We present transcriptome-wide alternative splicing patterns of Western Corn Rootworm midgut in response to feeding on eCry3.1Ab-expressing Corn using a comprehensive approach that combines both RNA-seq and SMRT transcript sequencing techniques. We found that 67.73% of multi-exon genes are alternatively spliced, which is consistent with the high transposable element content of the genome. One of the alternative splicing events we identified was a novel peritrophic matrix protein with two alternative splicing isoforms. Analysis of differential exon usage between resistant and susceptible colonies showed that in eCry3.1Ab-resistant Western Corn Rootworm, expression of one isoform was significantly higher than in the susceptible colony, while no significant differences between colonies were observed with the other isoform. ConclusionOur results provide the first survey of alternative splicing in Western Corn Rootworm and suggest that the observed alternatively spliced isoforms of peritrophic matrix protein may be associated with eCry3.1Ab resistance in Western Corn Rootworm.
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Characterization of Corn Root Factors to Improve Artificial Diet for Western Corn Rootworm (Coleoptera: Chrysomelidae) Larvae.
Journal of insect science (Online), 2019Co-Authors: Man P Huynh, Louis B Bjostad, E J Bernklau, Thomas A. Coudron, Kent S. Shelby, Bruce E HibbardAbstract:The Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is an important economic pest of maize (Zea mays L.) in North America and Europe. Previous efforts to formulate an artificial diet for Western Corn Rootworm larvae highlighted an important role of Corn root powder, which had a significant positive impact on several larval developmental traits. Unfortunately, this ingredient is not available for purchase. Toward the goal of developing an artificial diet for Western Corn Rootworm larvae with all ingredients readily accessible, we conducted research to isolate essential growth factors for larval development from Corn root powder to improve the performance of diet without Corn root powder. For all experiments, multiple life history parameters (survival, weight, and molting) were recorded from 15-d diet bioassays. Corn roots may contain factors that assist in larval growth, but some of these factors were not fully extracted by methanol and remained in the extracted root. Methanolic extracts significantly increased molting to second instar, but did not significantly increase survival, dry weight, or molting to third instar, suggesting the primary Corn root substituents affecting these factors cannot be extracted or other extraction methods may be required to extract the essential factors from Corn roots. We showed that whole Corn root powder was best when used in combination with all the other nutrient sources in the published Western Corn Rootworm formulation. Corn root powder made from proprietary seed and Viking seed has similar value.
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Effects of Cold Storage on Nondiapausing Eggs of the Western Corn Rootworm (Coleoptera: Chrysomelidae)
Journal of economic entomology, 2019Co-Authors: Ryan W Geisert, Dalton C Ludwick, Bruce E HibbardAbstract:Western Corn Rootworm, Diabrotica virgifera virgifera LeConte, became much easier to research with the development of a nondiapausing Rootworm strain. In the event that the eggs cannot be used immediately researchers have been known to delay egg hatch by storing the eggs at low temperatures. It is not well known how this technique could affect egg hatch or larval development, which could alter the results of an experiment. To test for this nondiapausing eggs of the Western Corn Rootworm were stored at low temperatures to test for potential negative effects on hatch and larval development. Eggs were stored in either soil or agar and placed in refrigerators set to 4 or 8.5°C. Nondiapausing eggs were exposed to the cold for 1, 2, or 4 wk and then placed in a chamber set to 25°C. Eggs were then tested for average hatch percentage in Petri dishes and average larval recovery from containers with seedling Corn. Results showed a significant reduction in percent hatch for eggs stored at 4°C for 4 wk. Larval recovery was significantly reduced in eggs stored for 4 wk at both 4 and 8.5°C. Within the treatments tested, egg storage for less than 4 wk in soil at 8.5°C provided the best hatch and larval recovery. Researchers wishing to store eggs may use these results to improve their rearing or testing of Western Corn Rootworm.
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Quantitative trait loci mapping of Western Corn Rootworm (coleoptera: Chrysomelidae) host plant resistance in two populations of doubled haploid lines in maize (Zea mays L.)
Journal of economic entomology, 2017Co-Authors: Martin O. Bohn, Kenton E. Dashiell, Juan J Marroquin, Sherry Flint-garcia, David B. Willmot, Bruce E HibbardAbstract:Over the last 70 yr, more than 12,000 maize accessions have been screened for their level of resistance to Western Corn Rootworm, Diabrotica virgifera virgifera (LeConte; Coleoptera: Chrysomelidae), larval feeding. Less than 1% of this germplasm was selected for initiating recurrent selection or other breeding programs. Selected genotypes were mostly characterized by large root systems and superior root regrowth after root damage caused by Western Corn Rootworm larvae. However, no hybrids claiming native (i.e., host plant) resistance to Western Corn Rootworm larval feeding are currently commercially available. We investigated the genetic basis of Western Corn Rootworm resistance in maize materials with improved levels of resistance using linkage disequilibrium mapping approaches. Two populations of topcrossed doubled haploid maize lines (DHLs) derived from crosses between resistant and susceptible maize lines were evaluated for their level of resistance in three to four different environments. For each DHL topcross an average root damage score was estimated and used for quantitative trait loci (QTL) analysis. We found genomic regions contributing to Western Corn Rootworm resistance on all maize chromosomes, except for chromosome 4. Models fitting all QTL simultaneously explained about 30 to 50% of the genotypic variance for root damage scores in both mapping populations. Our findings confirm the complex genetic structure of host plant resistance against Western Corn Rootworm larval feeding in maize. Interestingly, three of these QTL regions also carry genes involved in ascorbate biosynthesis, a key compound we hypothesize is involved in the expression of Western Corn Rootworm resistance.
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protandry of Western Corn Rootworm coleoptera chrysomelidae beetle emergence partially due to earlier egg hatch of males
Journal of the Kansas Entomological Society, 2017Co-Authors: Dalton C Ludwick, Anthony Zukoff, Matt Higdon, Bruce E HibbardAbstract:Abstract: The Western Corn Rootworm, Diabrotica virgifera virgifera LeConte, exhibits protandry. The contribution of pre-hatch development to protandry in Western Corn Rootworm was previously investigated with a small set of data from one population. To verify the contribution of pre-hatch development to protandry, more than 10,000 larvae from seven wild-type populations collected from across the Corn Belt were evaluated. Larvae were placed into containers on each day of egg hatch for each population and allowed to develop into adults. Duration of hatch for these populations ranged from 7 to 19 days with the percent of insects surviving to adulthood varying between 13 and 52%. For the first 25% of egg hatch, significantly more males emerge. Pre-hatch development does contribute to protandry, but overall the contribution is likely less than post-hatch development.
Michael E Gray - One of the best experts on this subject based on the ideXlab platform.
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Larval mortality and development for rotation‐resistant and rotation‐susceptible populations of Western Corn Rootworm on Bt Corn
Journal of Applied Entomology, 2014Co-Authors: Nicholas A. Tinsley, Ronald E Estes, Joseph L. Spencer, B. W. French, P. M. Schrader, Jarrad R. Prasifka, Michael E GrayAbstract:The Western Corn Rootworm, Diabrotica virgifera virgifera LeConte, is one of the most economically important insect pests threatening the production of Corn, Zea mays (L.), in the United States. Throughout its history, this insect has displayed considerable adaptability by overcoming a variety of pest management tactics, including the cultural practice of annual crop rotation. Since first reported in Illinois in the late 1980s, populations of the rotation-resistant Western Corn Rootworm have spread over a wide area of the eastern Corn Belt. Currently, little information is available concerning the interaction of rotation resistance with the use of genetically modified Corn expressing insecticidal toxins from Bacillus thuringiensis Berliner (Bt), a popular tactic for preventing larval injury and its associated yield loss. The goal of this greenhouse experiment was to determine whether rotation-resistant and rotation-susceptible Western Corn Rootworm larvae differ with respect to survival or development when exposed to single- or dual-toxin (pyramided) Bt Corn. Individual Corn plants were infested with 225 near-hatch eggs at the V5 (five leaf collar) growth stage. Larvae developed undisturbed on the root systems for 17 days, after which they were recovered using Berlese–Tullgren funnels. Surviving larvae were counted to estimate mortality, and head capsule widths were measured to assess development. Rotation-resistant and rotation-susceptible larvae had statistically similar mean levels of mortality and head capsule widths when exposed to both single-toxin (Cry3Bb1 or Cry34/35Ab1) and pyramided (Cry3Bb1+ Cry34/35Ab1) Bt Corn, suggesting that these two populations do not differ with respect to survival or development when exposed to Bt Corn. Additionally, the statistically similar mean levels of mortality for larvae exposed to single-toxin and pyramided Bt Corn suggest that pyramided Bt hybrids containing the Cry3Bb1 and Cry34/35Ab1 toxins do not result in additive mortality for Western Corn Rootworm larvae. Implications for management of this economically important pest are discussed.
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Adaptation and Invasiveness of Western Corn Rootworm: Intensifying Research
2009Co-Authors: Michael E Gray, Nicholas J. Miller, Thomas W. Sappington, Joachim Moeser, Martin O. BohnAbstract:The Western Corn Rootworm, Diabrotica virgifera virgifera LeConte, is an established insect pest of maize (Zea mays L.) in North America. The rotation of maize with another crop, principally soybeans, Glycine max (L.), was the primary management strategy utilized by North American producers and remained highly effective until the mid-1990s. In 1995, widespread and severe root injury occurred in east-central Illinois and northern Indiana maize fields that had been annually rotated with soy- beans on a regular basis for several decades. The failure of this cultural tactic from a pest management perspective was attributed to a behavioral adaptation by a variant Western Corn Rootworm that had lost fidelity to maize for egg laying. In 1992, an infestation of Western Corn Rootworm was found within a small maize field near the Belgrade Airport. By 2007, the presence of this insect pest had been confirmed in 20 European countries. More recent molecular studies have confirmed that at least three separate invasions (until 2004) of Western Corn Rootworms have occurred in Europe, increasing the risk that rotation-resistant Western Corn Rootworms will be introduced into a new continent. Although bio- logical control and use of conventional resistant maize hybrids have not achieved widespread success in the management of Western Corn root- worms in North America, these tactics are being evaluated in Europe.
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Adaptation and invasiveness of Western Corn Rootworm: intensifying research on a worsening pest.
Annual review of entomology, 2009Co-Authors: Michael E Gray, Nicholas J. Miller, Thomas W. Sappington, Joachim Moeser, Martin O. BohnAbstract:The Western Corn Rootworm, Diabrotica virgifera virgifera LeConte, is an established insect pest of maize (Zea mays L.) in North America. The rotation of maize with another crop, principally soybeans, Glycine max (L.), was the primary management strategy utilized by North American producers and remained highly effective until the mid-1990s. In 1995, widespread and severe root injury occurred in east-central Illinois and northern Indiana maize fields that had been annually rotated with soybeans on a regular basis for several decades. The failure of this cultural tactic from a pest management perspective was attributed to a behavioral adaptation by a variant Western Corn Rootworm that had lost fidelity to maize for egg laying. In 1992, an infestation of Western Corn Rootworm was found within a small maize field near the Belgrade Airport. By 2007, the presence of this insect pest had been confirmed in 20 European countries. More recent molecular studies have confirmed that at least three separate invasions (...
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Responses of transgenic maize hybrids to variant Western Corn Rootworm larval injury
Journal of Applied Entomology, 2007Co-Authors: Michael E Gray, Ronald E Estes, Kevin L. Steffey, Jared B. SchroederAbstract:In 2005 and 2006, transgenic insecticidal maize hybrids (YieldGard Rootworm, MON 863, Cry3Bbl, Vector ZMIR 13L) were evaluated for their ability to limit root injury caused by Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) larval feeding. Hybrids in each year of the experiment were planted in plots that had been devoted to a trap crop (late-planted maize interplanted with pumpkins) the previous growing season. All maize hybrids were provided by Monsanto Company and the genetic backgrounds remain unknown to the investigators. In 2005, the experiment was conducted in Urbana, Illinois. Urbana is located in east central Illinois, an area of the state in which a variant of the Western Corn Rootworm has overcome the pest management benefits of crop rotation. Variation in root injury was noted across the maize hybrids in 2005 and the level of pruning increased from 20 July to 9 August for most hybrids. In 2006, the experiment was conducted in two locations, Monmouth and Urbana, Illinois. Monmouth is located in north-Western Illinois and is within an area of the state in which densities of the variant of the Western Corn Rootworm are lower than in east-central Illinois. In 2006, variation in root protection was again observed across the maize hybrids. Root injury differences among the hybrids were more prominent at the Urbana site. Similar to the previous year, root injury increased from the third week in July to the first week of August at both locations with this increase most noticeable at the Urbana location. We hypothesize that the variant Western Corn Rootworm may be able to inflict more root injury to these transgenic insecticidal maize hybrids than the non-variant population of this species.
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Unbalanced Nested Component Error Model and the Value of Soil Insecticide and Bt Corn for Controlling Western Corn Rootworm
2007Co-Authors: Juan Yang, Michael E Gray, Paul D. Mitchell, Kevin L. SteffeyAbstract:We describe four recently developed panel data estimators for unbalanced and nested data, a common problem for economic and experimental data. We estimate a Western Corn Rootworm damage function with each estimator, including separate parameters for random effects from year, location, and experimental errors. We then use each estimator to assess the cost of the Western Corn Rootworm soybean variant and the net benefit of soil insecticide and Bt Corn for controlling this pest. At current prices, we find that soil insecticide generates a net loss ranging about $0.50-$3.25/ac, while Bt Corn generates a net benefit ranging $2.50-$7.00/ac.
Ram B. Shrestha - One of the best experts on this subject based on the ideXlab platform.
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Inheritance and Fitness Costs of Cry3Bb1 Resistance in Diapausing Field Strains of Western Corn Rootworm (Coleoptera: Chrysomelidae).
Journal of economic entomology, 2020Co-Authors: Ram B. Shrestha, Aaron J. GassmannAbstract:Field-evolved resistance to Cry3Bb1 Corn by Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Colleoptera: Chrysomellidae), has been reported in field populations in Iowa, Illinois, Nebraska, and Minnesota. Inheritance and fitness costs associated with Cry3Bb1 resistance have been determined for non-diapausing laboratory strains of Western Corn Rootworm with either laboratory-selected resistance or field-derived resistance. However, information on inheritance and fitness costs of Cry3Bb1 resistance in the diapausing field populations is lacking. In this study, we determined the inheritance of Cry3Bb1 resistance for four diapausing field strains of Western Corn Rootworm using plant-based bioassays. We also determined the fitness costs for eight diapausing field populations in a greenhouse experiment. We found that Cry3Bb1 resistance was an autosomal trait and that the inheritance of resistance was mostly non-recessive; however, there was some variation in the dominance of Cry3Bb1 resistance. We did not find evidence of fitness costs affecting survival to adulthood, developmental rate, or adult dry mass. However, we did detect a fitness cost affecting adult size. The results of this study will add to the current understanding of field-evolved resistance to Cry3Bb1 Corn by Western Corn Rootworm and help in developing better strategies to manage resistance.
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field evolved resistance by Western Corn Rootworm to cry34 35ab1 and other bacillus thuringiensis traits in transgenic maize
Pest Management Science, 2020Co-Authors: Aaron J. Gassmann, Ram B. Shrestha, Abigail L Kropf, Coy R. St. Clair, Ben D BrenizerAbstract:Background Transgenic crops producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage agricultural insect pests. However, widespread adoption of Bt crops has led to the evolution of Bt resistance. The Western Corn Rootworm, Diabrotica virgifera virgifera, is among the most serious pests of maize in the midWestern United States and is currently managed with Bt maize. To date, there is evidence of field-evolved resistance to all Bt toxins used to manage this pest. While Western Corn Rootworm resistance to Cry3Bb1, and the closely related mCry3A and eCry3.1Ab traits, is widely distributed within the Midwest, fewer cases of Cry34/35Ab1 resistance have been observed, and planting of Cry34/35Ab1 maize is one of the methods used to manage Cry3-resistant Rootworm. Results We found that fields with high levels of root injury to Cry34/35Ab1 maize by Western Corn Rootworm were associated with Cry34/35Ab1-resistant Western Corn Rootworm. Additionally, a population not associated with high levels of root injury was found to be resistant to Cry34/35Ab1. In all cases, populations that were resistant to Cry34/35Ab1 also were resistant to Cry3 traits. Conclusions Western Corn Rootworm resistance to Cry34/35Ab1 has continued to persist in the agricultural landscape and has likely increased. The presence of Rootworm populations with resistance to all available Bt traits threatens the utility of current and future transgenic technologies to manage this pest. Decreased reliance on Cry34/35Ab1 and better use of integrated pest management will be essential to preserve Bt susceptibility in Western Corn Rootworm. © 2019 Society of Chemical Industry.
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Field-evolved resistance by Western Corn Rootworm to Cry34/35Ab1 and other Bacillus thuringiensis traits in transgenic maize.
Pest management science, 2019Co-Authors: Aaron J. Gassmann, Ram B. Shrestha, Abigail L Kropf, Coy R. St. Clair, Ben D BrenizerAbstract:Background Transgenic crops producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage agricultural insect pests. However, widespread adoption of Bt crops has led to the evolution of Bt resistance. The Western Corn Rootworm, Diabrotica virgifera virgifera, is among the most serious pests of maize in the midWestern United States and is currently managed with Bt maize. To date, there is evidence of field-evolved resistance to all Bt toxins used to manage this pest. While Western Corn Rootworm resistance to Cry3Bb1, and the closely related mCry3A and eCry3.1Ab traits, is widely distributed within the Midwest, fewer cases of Cry34/35Ab1 resistance have been observed, and planting of Cry34/35Ab1 maize is one of the methods used to manage Cry3-resistant Rootworm. Results We found that fields with high levels of root injury to Cry34/35Ab1 maize by Western Corn Rootworm were associated with Cry34/35Ab1-resistant Western Corn Rootworm. Additionally, a population not associated with high levels of root injury was found to be resistant to Cry34/35Ab1. In all cases, populations that were resistant to Cry34/35Ab1 also were resistant to Cry3 traits. Conclusions Western Corn Rootworm resistance to Cry34/35Ab1 has continued to persist in the agricultural landscape and has likely increased. The presence of Rootworm populations with resistance to all available Bt traits threatens the utility of current and future transgenic technologies to manage this pest. Decreased reliance on Cry34/35Ab1 and better use of integrated pest management will be essential to preserve Bt susceptibility in Western Corn Rootworm. © 2019 Society of Chemical Industry.
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Field and Laboratory Studies of Resistance to Bt Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae).
Journal of economic entomology, 2019Co-Authors: Ram B. Shrestha, Aaron J. GassmannAbstract:Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), has developed resistance to transgenic Corn that produces the insecticidal toxin Cry3Bb1 derived from the bacterium Bacillus thuringiensis (Bacillales: Bacillaceae) (Bt), with cross-resistance extending to Corn with Bt toxins mCry3A and eCry3.1Ab. Additionally, some populations of Western Corn Rootworm have evolved resistance to Cry34/35Ab1 Corn. We conducted a 2-yr field and laboratory study that included three field locations: 1) Bt-susceptible population, 2) field with a recent history of Cry3Bb1 resistance, and 3) field with a long-term history of Cry3Bb1 resistance. The population with recently evolved Cry3Bb1 resistance showed resistance to Cry3Bb1 Corn in both laboratory bioassays and field evaluations; by contrast, the population with a long-term history of Cry3Bb1 resistance showed resistance, in both laboratory and field experiments to Cry3Bb1 Corn and Corn with a pyramid of mCry3A plus eCry3.1Ab Corn. Field-based evaluations also showed that the field population with a long-term history of Cry3Bb1 resistance imposed higher root injury to Cry3Bb1 Corn and the pyramid of mCry3A plus eCry3.1Ab compared with the susceptible control. The results of this study are discussed in the context of developing strategies to manage Western Corn Rootworm in areas where populations have evolved resistance to Cry3Bb1 Corn.
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Effects of field history on resistance to Bt maize by Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae).
PloS one, 2018Co-Authors: Ram B. Shrestha, Mike W. Dunbar, Bryan Wade French, Aaron J. GassmannAbstract:Western Corn Rootworm, Diabrotica virgifera virgifera LeConte, has evolved resistance to transgenic maize, Zea maize L., that produces the insecticidal protein Cry3Bb1, which is derived from the bacterium Bacillus thuringiensis. We hypothesized that the level of Cry3Bb1 resistance in populations of Western Corn Rootworm could be influenced by farming practices. To test this hypothesis, we evaluated the effect of field history on resistance to Cry3Bb1 maize by Western Corn Rootworm. In 2013 and 2014, Rootworm adults were collected from the four types of maize fields: 1) current problem fields, 2) past problem fields, 3) rotated maize fields, and 4) continuous maize fields. Those field populations along with seven Bt-susceptible control populations were tested for Cry3Bb1 resistance with both plant-based and diet-based bioassays. All field populations were resistant to Cry3Bb1 regardless of field history, however, some variation in the degree of resistance was found. For all categories of field populations, larval survivorship on Cry3Bb1 maize was significantly higher than control populations, and did not differ from survival on non-Bt maize. Evidence of resistance to Cry3Bb1 maize in plant-based bioassays was further supported by diet-based bioassays and we found a positive relationship between LC50 values from diet-based bioassays and the larval survivorship in plant-based bioassays. This study provides evidence of Cry3Bb1 resistance throughout the agricultural landscape studied, irrespective of the field history, and highlights the need for improved resistance management approaches, such as better use of integrated pest management to better delay pest resistance.
Mike W. Dunbar - One of the best experts on this subject based on the ideXlab platform.
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Effects of field history on resistance to Bt maize by Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae).
PloS one, 2018Co-Authors: Ram B. Shrestha, Mike W. Dunbar, Bryan Wade French, Aaron J. GassmannAbstract:Western Corn Rootworm, Diabrotica virgifera virgifera LeConte, has evolved resistance to transgenic maize, Zea maize L., that produces the insecticidal protein Cry3Bb1, which is derived from the bacterium Bacillus thuringiensis. We hypothesized that the level of Cry3Bb1 resistance in populations of Western Corn Rootworm could be influenced by farming practices. To test this hypothesis, we evaluated the effect of field history on resistance to Cry3Bb1 maize by Western Corn Rootworm. In 2013 and 2014, Rootworm adults were collected from the four types of maize fields: 1) current problem fields, 2) past problem fields, 3) rotated maize fields, and 4) continuous maize fields. Those field populations along with seven Bt-susceptible control populations were tested for Cry3Bb1 resistance with both plant-based and diet-based bioassays. All field populations were resistant to Cry3Bb1 regardless of field history, however, some variation in the degree of resistance was found. For all categories of field populations, larval survivorship on Cry3Bb1 maize was significantly higher than control populations, and did not differ from survival on non-Bt maize. Evidence of resistance to Cry3Bb1 maize in plant-based bioassays was further supported by diet-based bioassays and we found a positive relationship between LC50 values from diet-based bioassays and the larval survivorship in plant-based bioassays. This study provides evidence of Cry3Bb1 resistance throughout the agricultural landscape studied, irrespective of the field history, and highlights the need for improved resistance management approaches, such as better use of integrated pest management to better delay pest resistance.
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evidence of resistance to cry34 35ab1 Corn by Western Corn Rootworm coleoptera chrysomelidae root injury in the field and larval survival in plant based bioassays
Journal of Economic Entomology, 2016Co-Authors: Aaron J. Gassmann, Wade B French, Ram B. Shrestha, Siva R. K. Jakka, Mike W. Dunbar, David A. Ingber, Eric H. Clifton, Aubrey R. Paolino, Kenneth MasloskiAbstract:Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a serious pest of Corn in the United States, and recent management of Western Corn Rootworm has included planting of Bt Corn. Beginning in 2009, Western Corn Rootworm populations with resistance to Cry3Bb1 Corn and mCry3A Corn were found in Iowa and elsewhere. To date, Western Corn Rootworm populations have remained susceptible to Corn producing Bt toxin Cry34/35Ab1. In this study, we used single-plant bioassays to test field populations of Western Corn Rootworm for resistance to Cry34/35Ab1 Corn, Cry3Bb1 Corn, and mCry3A Corn. Bioassays included nine Rootworm populations collected from fields where severe injury to Bt Corn had been observed and six control populations that had never been exposed to Bt Corn. We found incomplete resistance to Cry34/35Ab1 Corn among field populations collected from fields where severe injury to Corn producing Cry34/35Ab1, either singly or as a pyramid, had been observed. Additionally, resistance to Cry3Bb1 Corn and mCry3A Corn was found among the majority of populations tested. These first cases of resistance to Cry34/35Ab1 Corn, and the presence of resistance to multiple Bt toxins by Western Corn Rootworm, highlight the potential vulnerability of Bt Corn to the evolution of resistance by Western Corn Rootworm. The use of more diversified management practices, in addition to insect resistance management, likely will be essential to sustain the viability of Bt Corn for management of Western Corn Rootworm.
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Evidence of Resistance to Cry34/35Ab1 Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae): Root Injury in the Field and Larval Survival in Plant-Based Bioassays.
Journal of economic entomology, 2016Co-Authors: Aaron J. Gassmann, B. Wade French, Ram B. Shrestha, Siva R. K. Jakka, Mike W. Dunbar, David A. Ingber, Eric H. Clifton, Aubrey R. Paolino, Kenneth Masloski, John W. DoundaAbstract:Western Corn Rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a serious pest of Corn in the United States, and recent management of Western Corn Rootworm has included planting of Bt Corn. Beginning in 2009, Western Corn Rootworm populations with resistance to Cry3Bb1 Corn and mCry3A Corn were found in Iowa and elsewhere. To date, Western Corn Rootworm populations have remained susceptible to Corn producing Bt toxin Cry34/35Ab1. In this study, we used single-plant bioassays to test field populations of Western Corn Rootworm for resistance to Cry34/35Ab1 Corn, Cry3Bb1 Corn, and mCry3A Corn. Bioassays included nine Rootworm populations collected from fields where severe injury to Bt Corn had been observed and six control populations that had never been exposed to Bt Corn. We found incomplete resistance to Cry34/35Ab1 Corn among field populations collected from fields where severe injury to Corn producing Cry34/35Ab1, either singly or as a pyramid, had been observed. Additionally, resistance to Cry3Bb1 Corn and mCry3A Corn was found among the majority of populations tested. These first cases of resistance to Cry34/35Ab1 Corn, and the presence of resistance to multiple Bt toxins by Western Corn Rootworm, highlight the potential vulnerability of Bt Corn to the evolution of resistance by Western Corn Rootworm. The use of more diversified management practices, in addition to insect resistance management, likely will be essential to sustain the viability of Bt Corn for management of Western Corn Rootworm.
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Western Corn Rootworm and bt maize challenges of pest resistance in the field
GM crops & food, 2012Co-Authors: Aaron J. Gassmann, Ryan S. Keweshan, Jennifer L Petzoldmaxwell, Mike W. DunbarAbstract:Crops genetically engineered to produce insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) manage many key insect pests while reducing the use of conventional insecticides. One of the primary pests targeted by Bt maize in the United States is the Western Corn Rootworm, Diabrotica virgifera virgifera LeConte. Beginning in 2009, populations of Western Corn Rootworm were identified in Iowa, USA that imposed severe root injury to Cry3Bb1 maize. Subsequent laboratory bioassays revealed that these populations were resistant to Cry3Bb1 maize, with survival on Cry3Bb1 maize that was three times higher than populations not associated with such injury. Here we report the results of research that began in 2010 when Western Corn Rootworm were sampled from 14 fields in Iowa, half of which had root injury to Cry3Bb1 maize of greater than 1 node. Of these samples, sufficient eggs were collected to conduct bioassays on seven populations. Laboratory bioassays revealed that these 2010 populations had surviv...
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Field-Evolved Resistance to Bt Maize by Western Corn Rootworm
PloS one, 2011Co-Authors: Aaron J. Gassmann, Jennifer L. Petzold-maxwell, Ryan S. Keweshan, Mike W. DunbarAbstract:Background Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are planted on millions of hectares annually, reducing the use of conventional insecticides and suppressing pests. However, the evolution of resistance could cut short these benefits. A primary pest targeted by Bt maize in the United States is the Western Corn Rootworm Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).
