Inheritance, Fitness Costs, and Potential Mechanisms of Resistance for Western Corn Rootwork Larvae Surviving Bt Corn PDF Download
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Author: Ryan W. Geisert Publisher: ISBN: Category : Languages : en Pages : 102
Book Description
The western corn rootworm, Diabrotica virgifera virgifera LeConte, has developed resistance to most control tactics used to manage it. Transgenic corn varieties that express insecticidal proteins from the bacterium Bacillus thuringiensis Berliner (Bt), cause mortality to target pests when ingested. In an attempt to delay resistance formation to these Bt products, the Environmental Protection Agency mandates the development of an insect resistance management program prior to registration for commercial sale. Despite plans to delay resistance being in place, resistance has developed in the field for both Cry3Bb1 and mCry3A-expressing hybrids. Resistance to these products could be due to physiological adaptations or through behavioral avoidance of the toxin in the plant. For the first portion of this work, we investigated a behavioral avoidance hypothesis for resistance. We hypothesized that later hatching western corn rootworm larvae could utilize previous feeding damage on Bt corn roots by early hatching larvae as an entry point into the root cortex containing lower levels of the Bt protein. Field and greenhouse tests involving infestation staggering to facilitate previous feeding damage did not support our hypothesis and did not indicate any effect of previous root feeding on the ability of this pest to establish on Bt plants and cause damage. We also evaluated resistance dynamics in the western corn rootworm in response to the most recent Bt protein commercialized for rootworm management, eCry3.1Ab. For one experiment, an eCry3.1Ab-selected and a paired control western corn rootworm colony were utilized to determine the potential fitness costs associated with eCry3.1Ab resistance. Adult longevity, egg viability, and larval development time results indicated a lack of fitness costs associated with eCry3.1Ab resistance in the western corn rootworm. Reciprocally crossed colonies of the eCry3.1Ab-selected and control colonies were created in order to evaluate whether the resistance trait to eCry3.1Ab was recessive, dominant, or something in between. Each reciprocal cross and their parent colonies were evaluated in diet toxicity and plant assays. Results indicated that the eCry3.1Ab resistance trait we selected for under laboratory conditions is dominantly inherited.
Author: Ryan W. Geisert Publisher: ISBN: Category : Languages : en Pages : 102
Book Description
The western corn rootworm, Diabrotica virgifera virgifera LeConte, has developed resistance to most control tactics used to manage it. Transgenic corn varieties that express insecticidal proteins from the bacterium Bacillus thuringiensis Berliner (Bt), cause mortality to target pests when ingested. In an attempt to delay resistance formation to these Bt products, the Environmental Protection Agency mandates the development of an insect resistance management program prior to registration for commercial sale. Despite plans to delay resistance being in place, resistance has developed in the field for both Cry3Bb1 and mCry3A-expressing hybrids. Resistance to these products could be due to physiological adaptations or through behavioral avoidance of the toxin in the plant. For the first portion of this work, we investigated a behavioral avoidance hypothesis for resistance. We hypothesized that later hatching western corn rootworm larvae could utilize previous feeding damage on Bt corn roots by early hatching larvae as an entry point into the root cortex containing lower levels of the Bt protein. Field and greenhouse tests involving infestation staggering to facilitate previous feeding damage did not support our hypothesis and did not indicate any effect of previous root feeding on the ability of this pest to establish on Bt plants and cause damage. We also evaluated resistance dynamics in the western corn rootworm in response to the most recent Bt protein commercialized for rootworm management, eCry3.1Ab. For one experiment, an eCry3.1Ab-selected and a paired control western corn rootworm colony were utilized to determine the potential fitness costs associated with eCry3.1Ab resistance. Adult longevity, egg viability, and larval development time results indicated a lack of fitness costs associated with eCry3.1Ab resistance in the western corn rootworm. Reciprocally crossed colonies of the eCry3.1Ab-selected and control colonies were created in order to evaluate whether the resistance trait to eCry3.1Ab was recessive, dominant, or something in between. Each reciprocal cross and their parent colonies were evaluated in diet toxicity and plant assays. Results indicated that the eCry3.1Ab resistance trait we selected for under laboratory conditions is dominantly inherited.
Author: Sarah N. Zukoff Publisher: ISBN: Category : Corn Languages : en Pages : 133
Book Description
The Environmental Protection Agency recently registered seed blend refuges for two of the transgenic Bt corn products targeting the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte. Larval movement between Bt and isoline plants can be detrimental to resistance management for high dose Bt products because the insect larvae will potentially be exposed to sublethal amounts of the Bt, however, the effect of this movement on low to moderate dose products is unknown. All current rootworm products are low dose. The main criteria for whether movement by WCR larvae between isoline and Bt corn plants will influence the development of resistance is whether or not selection for resistance is taking place. We found that movement between isoline and SmartStax[registered trademark] hybrid plants did occur in seed blend scenarios in our field study. The majority of plant damage to the SmartStax plants occurred when the larvae moved from surrounding infested isoline plants moved late in their development. These older, larger larvae are all able to tolerate the Bt in the plants, therefore resistance will likely not develop in these larvae. In a similar experiment, movement also occurred between Agrisure® Duracad[trademark] and isoline plants in seed blend scenarios, however the damage was low for all treatments. With isoline plants being mixed with Bt plants in seed blend refuges, host recognition behavior of the western corn rootworm on Bt and isoline plants is also important to understand. There were no differences between the host recognition behavior of WCR larvae after exposure to mCry3A, Cry3Bb1, Cry34/35Ab1, or their isoline corn hybrids, therefore all hybrids were perceived as hosts by WCR larvae. With all the hybrids on the currently registered being pyramided by different companies to control rootworms, the potential for cross resistance between these hybrids was evaluated using field resistant and susceptible populations. Based on the data from laboratory and greenhouse assays, the potential for cross resistance between mCry3A and Cry3Bb1 might be likely, but not between these hybrids and Cry34/35Ab1. Information gathered in this study provides important behavioral information on western corn rootworms that will aid in making decisions involving Bt corn hybrids.
Author: Dalton C. Ludwick Publisher: ISBN: Category : Languages : en Pages : 135
Book Description
Western corn rootworm (Diabrotica virgifera virgifera LeConte) has been a pest of corn (Zea mays L.) for more than one century. In that time, this insect has spread across the United States and has also had several introductions into Europe. Though corn growers have applied a number of control tactics over the years, including crop rotation, synthetic insecticides, and transgenic corn, this insect is persistently an issue for much of the corn growing areas in the United States and Europe. Western corn rootworm is infamous for its ability to overcome the tactics that are used against it, several times within a single decade. Transgenic corn expressing one or more protein(s) from Bacillus thuringiensis Berliner (Bt) have been used against this insect for more than one decade. Western corn rootworm had developed resistance to three of the four proteins (Cry3Bb1, mCry3A, and eCry3.1Ab) and had been documented before the start of this dissertation. Immediately prior to the start of this dissertation, information existed that resistance to the fourth protein (Cry34/35Ab1) may have occurred in a Minnesota population. In this dissertation, we placed insects from control colonies or the field population in containers with corn expressing the Cry34/35Ab1 protein or in containers with artificial diet covered by the protein. The results of these three experiments indicated that incomplete resistance to Cry34/35Ab1 and Cry3Bb1 had occurred. The artificial diets used in the first experiment are proprietary and owned by separate companies. Efforts in separate studies led to the formulation of an improved artificial for western corn rootworm larvae which is now available to the public. This single, artificial diet was tested for its ability to detect resistance to the different proteins currently targeting western corn rootworm. Laboratory colonies of insects selected for resistance to each protein were compared to susceptible insects on the new diet for their ability to survive and develop. The proprietary diets were also used to make comparisons about the similarity of the diets to the new, public diet. The new diet performed similarly to proprietary diets in terms of mortality and developmental rates. Indeed, the new diet was able to detect resistance to all proteins and documented strong differences between Cry34/35Ab1-resistant insects and susceptible insects for the first time. Lastly, we investigated which bacteria were associated with this insect. Laboratory insects were raised in two geographically and microbially distinct soils on non-Bt corn. Insects were collected at different time points to understand which bacteria were present in each life stage and across all life stages. Bacteria in soil samples were also identified and compared to those found in the insect to determine which bacteria were unique to the insect. These results suggest that 16 different bacteria are found in every western corn rootworm, some of which appear to only occur in the insect. The knowledge of bacteria associated with western corn rootworm may one day help us better understand the mechanisms of Bt resistance and how to better optimize nutrition.
Author: Stefan Vidal Publisher: CABI ISBN: 0851990703 Category : Science Languages : en Pages : 326
Book Description
Western Corn Rootworm, Diabrotica virgifera virgifera LeConte, has been a major economic pest of maize in the Americas for many years. However, since the early 1990's it has become an increasing threat to crops in Europe and is expected to spread to all maize growing areas of the continent. This book provides a comprehensive review of current knowledge of the biology and ecology of this insect pest and how it might be managed in order to limit its damage as it spreads into new agroecological areas. Cultural, biotechnical, and biological control measures are addressed, as are ecological baseline data such as population dynamics, economic thresholds and aspects of its behaviour. The book also examines the potential of plant protection techniques currently used in North America to be applied in Europe.
Author: David W. Onstad Publisher: Academic Press ISBN: 0123972337 Category : Science Languages : en Pages : 561
Book Description
Neither pest management nor resistance management can occur with only an understanding of pest biology. For years, entomologists have understood, with their use of economic thresholds, that at least a minimal use of economics was necessary for proper integrated pest management. IRM is even more complicated and dependent on understanding and using socioeconomic factors. The new edition of Insect Resistance Management addresses these issues and much more. Many new ideas, facts and case studies have been developed since the previous edition of Insect Resistance Management published. With a new chapter focusing on Resistance Mechanisms Related to Plant-incorporated Toxins and heavily expanded revisions of several existing chapters, this new volume will be an invaluable resource for IRM researchers, practitioners, professors and advanced students. Authors in this edition include professors at major universities, leaders in the chemical and seed industry, evolutionary biologists and active IRM practitioners. This revision also contains more information about IRM outside North America, and a modeling chapter contains a large new section on uncertainty analysis, a subject recently emphasized by the U.S. Environmental Protection Agency. The final chapter contains a section on insecticidal seed treatments. No other book has the breadth of coverage of Insect Resistance Management, 2e. It not only covers molecular to economic issues, but also transgenic crops, seed treatments and other pest management tactics such as crop rotation. Major themes continuing from the first edition include the importance of using IRM in the integrated pest management paradigm, the need to study and account for pest behavior, and the influence of human behavior and decision making in IRM. Provides insights from the history of insect resistance management (IRM) to the latest science Includes contributions from experts on ecological aspects of IRM, molecular and population genetics, economics, and IRM social issues Offers biochemistry and molecular genetics of insecticides presented with an emphasis on recent research Encourages scientists and stakeholders to implement and coordinate strategies based on local social conditions
Author: Ted A. Wilson Publisher: ISBN: Category : Languages : en Pages : 216
Book Description
Monsanto Co. (St. Louis, MO) has received approval for the commercial sale of transgenic corn (Zea mays L.) modified to produce insecticidal protein (Cry3Bb1) from the soil bacterium Bacillus thuringiensis Berliner (Bt) for control of the western corn rootworm larvae, Diabrotica virgifera virgifera LeConte and northern corn rootworm, D. barberi Smith and Lawrence; southern corn rootworm. This new technology could help reduce the amount of pesticides applied to corn fields for control of these pests and provides an alternative management strategy. The first objective was to determine if the fitness of beetles surviving from transgenic corn was affected. Female adults emerging from transgenic treatments were the same size as females from terbufos and isoline treatments but laid fewer eggs. Transgenic corn did not affect percent egg hatch. Females from YieldGard Rootworm and terbufos flew significantly shorter distances than females from isoline and YieldGard Plus treatments. Virgin females did not fly sustained flights. Mated females from isoline and transgenic treatments flew farther than virgin females. The second objective was to examine similar questions but of adult beetles who had been exposed to the leaves and silks of transgenic plants. Beetles exposed to leaves or silks of transgenic plants did not fly significantly different than beetles exposed to nontransgenic plants. Beetles caged on leaves of transgenic plants for 5 days had higher mortality, consumed less leaf area, and laid fewer eggs than beetles caged on leaves of nontransgenic plants. Very little mortality occurred in beetles exposed to the silks of transgenic plants. Exposure to silks of transgenic plants did not affect egg laying or adult longevity. The third objective was to evaluate farmer perceptions and attitudes of transgenic corn using a survey. When asked if they would plant transgenic corn protected again the corn rootworm, 35.0% responded they would while 40.5% said they were unsure. The two biggest concerns farmers had of transgenic corn was the ability to sell harvested grain and additional technology fees. Farmers felt that less insecticide in the environment and less insecticide exposure to farmers were significant benefits of transgenic corn. The most common refuge-planting options farmers favored were adjacent fields and split fields.
Author: National Academies of Sciences, Engineering, and Medicine Publisher: National Academies Press ISBN: 0309437385 Category : Science Languages : en Pages : 607
Book Description
Genetically engineered (GE) crops were first introduced commercially in the 1990s. After two decades of production, some groups and individuals remain critical of the technology based on their concerns about possible adverse effects on human health, the environment, and ethical considerations. At the same time, others are concerned that the technology is not reaching its potential to improve human health and the environment because of stringent regulations and reduced public funding to develop products offering more benefits to society. While the debate about these and other questions related to the genetic engineering techniques of the first 20 years goes on, emerging genetic-engineering technologies are adding new complexities to the conversation. Genetically Engineered Crops builds on previous related Academies reports published between 1987 and 2010 by undertaking a retrospective examination of the purported positive and adverse effects of GE crops and to anticipate what emerging genetic-engineering technologies hold for the future. This report indicates where there are uncertainties about the economic, agronomic, health, safety, or other impacts of GE crops and food, and makes recommendations to fill gaps in safety assessments, increase regulatory clarity, and improve innovations in and access to GE technology.
Author: Peter Gacii Chege Publisher: ISBN: Category : Corn Languages : en Pages :
Book Description
With the increasing adoption of transgenic maize with resistance to rootworms, combined with glyphosate tolerance, as a control tactic for western corn rootworm, Diabrotica virgifera virgifera LeConte, an understanding of the effect of alternate host plants on rootworm population dynamics is critical to the formulation of effective IRM programs. Three studies were conducted to evaluate the effects of alternate host plant phenology on the survivorship, growth, development, and host searching behavior of larvae, as well as the effect of initial feeding of larvae on an alternate host followed by movement to rootworm resistant transgenic corn on beetle emergence and reproductive fitness of emerged female beetles. Initial feeding on alternate hosts followed by movement to Bt maize increased beetle emergence from Bt maize, fecundity of those that survived, and the number of viable eggs produced. In greenhouse trials, western corn rootworm larvae had significantly greater survival on younger grassy weeds (4 to 6 weeks old) versus older grassy weeds. In behavioral tests, western corn rootworm larvae recognized younger roots (4 week old) as hosts but did not recognize older roots (7 or 10 week old) as hosts. Phenological changes in grassy weeds could encourage movement of larvae from weeds to transgenic maize.
Author: Paul Christou Publisher: Springer ISBN: 9781461457961 Category : Technology & Engineering Languages : en Pages : 1869
Book Description
Gathering some 90 entries from the Encyclopedia of Sustainability Science and Technology, this book covers animal breeding and genetics for food, crop science and technology, ocean farming and sustainable aquaculture, transgenic livestock for food and more.
Author: Ryan W. Geisert
Author: Ryan W. Geisert
Author: Sarah N. Zukoff
Author: Dalton C. Ludwick
Author: Francis Marion Webster
Author: Stefan Vidal
Author: David W. Onstad
Author: Ted A. Wilson
Author: National Academies of Sciences, Engineering, and Medicine
Author: Peter Gacii Chege
Author: Paul Christou