Download or read book Impact of Alternate Host Phenology Amd Alternate Hose transgenic Corn Interactions on the Western Corn Rootworm Coleoptera Chrysomelidae written by Peter Gacii Chege and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Effect of Monsanto Corn Event MON88017 Adult Diet and Host Phenology on Selected Western Corn Rootworm Diabrotica Virgifera LeConte Life History Traits written by Stephen Thomas Young and published by . This book was released on 2009 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Western Corn Rootworm written by Stefan Vidal and published by CABI. This book was released on 2005 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Effects of Western Corn Rootworm Larval Feeding Drought and Their Interaction on Maize Performance and Rootworm Development written by Mervat Ahmed Badawy Mahmoud and published by . This book was released on 2015 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: The western corn rootworm, Diabrotica virgifera virgifera LeConte can affect water relations and yield of its host, maize (Zea mays L.), under normal soil moisture. Drought stress negatively affects plant growth and yield. Anecdotal data have suggested that the effect of western corn rootworm is greater under drought and the effect of drought is greater under rootworm infestations, but few experiments have controlled both moisture and rootworm levels. We hypothesized that if drought and rootworms both occur, there would be a negative synergistic effect on maize growth and yield. To test this hypothesis, a series of greenhouse and field experiments were performed. Greenhouse experiments tested only one maize line at three different moisture levels and three different western corn rootworm infestation levels. This was done not only with neonate larvae, but also second instar larvae and eggs in separate, full experiments. Overall, the greenhouse results indicated that under the conditions of these experiments, the effect of drought was greater than the effect of western corn rootworm and the interactions between soil moisture level in western corn rootworm infestation level did not affect plant traits such as water potential, stomatal conductance, shoot air-dried weight, and root air-dried weight in most of the trials. Rootworms did add some interesting complexity to the greenhouse experiment. For instance, plants without western corn rootworm were more stressed than the moderate western corn rootworm infestation for the drought treatments in the third greenhouse experiment. Drought also impacted western corn rootworm larvae in the same experiment, but only when the larvae were already stressed at the highest infestation level. Field studies also were conducted in 2012, 2013, and 2014 with treatments varying soil moisture levels, western corn rootworm infestation levels, and maize hybrids with and without tolerance to drought and rootworm pressure. In 2012 and 2013, western corn rootworm infestation significantly impacted yield, but its impact on yield was much less than the effect of drought. When under drought and rootworm pressure, the Bt+AQUAmax hybrid with tolerance to western corn rootworm and drought was generally higher yielding and significantly less water-stressed than other hybrids. Root damage ratings were not significantly impacted by drought or its interactions with western corn rootworm infestation. Both drought and western corn rootworm affected water potential, stomatal conductance, root complexity, and beetle emergence. The magnitude of the effect of drought versus western corn rootworm infestation level varied depending on the factor being evaluated, but in general drought had a greater effect on maize growth factors. We must reject our hypothesis that rootworms and drought have a negative synergistic effect on maize growth and yield under the conditions of our study.
Download or read book Corn Rootworm Phenology and Influence of Culture Practices written by Norma Brenes Solano and published by . This book was released on 1994 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multipartite Interactions Among Western Corn Rootworms Diabrotica Virgifera Virgifera LeConte Coleoptera Chrysomelidae Transgenic Corn Zea Mays L Poales Poaceae and Soil Microbes written by Stephanie L Gorski and published by . This book was released on 2015 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fitness of the Western Corn Rootworm Diabrotica Virgifera Virgifera LeConte Exposed to Transgenic Plants and Farmer Perceptions of Transgenic Corn written by Ted A. Wilson and published by . This book was released on 2003 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book The Impact of Western Corn Rootworm Coleoptera Chrysomelidae on Pollination Success in Seed Corn Production Fields written by Michael D. Culy and published by . This book was released on 1987 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Population Dynamics and Oviposition of the Northern Corn Rootworm Diabrotica Barberi written by Steven Edward Naranjo and published by . This book was released on 1987 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spatial Variation in Western Corn Rootworm Coleoptera Chrysomelidae Susceptibility to Bacillus Thuringiensis Corn Events in Nebraska written by Jordan D. Reinders and published by . This book was released on 2017 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an economically important pest species of field corn (Zea mays L.) in the U.S. Corn Belt. Yield losses and control costs exceed greater than $1 billion annually. Over the past 10+ years, growers have adopted transgenic corn hybrids expressing rootworm-active Bacillus thuringiensis (Bt) proteins as a primary WCR management tactic. Field-evolved resistance to Cry3Bb1 and mCry3A proteins expressed in single-trait Bt hybrids has been confirmed in some areas of Nebraska. Growers have used different tactics as needed to prevent or mitigate resistance, resulting in a mosaic of selection pressure placed on local populations. Currently, research is needed to characterize WCR susceptibility to these Bt toxins on a local spatial scale. Therefore, this study was conducted to characterize spatial variation in WCR susceptibility to Bt corn events in two corn-intensive production areas of Nebraska. Single-plant larval bioassays were conducted in 2016 and 2017 to characterize the susceptibility of populations from pre-established grids in Keith and Buffalo counties to single-trait Cry3Bb1 and mCry3A proteins. Bioassay results confirmed a mosaic of susceptibility to Cry3Bb1 and mCry3A existed within the two landscapes. Patterns at several spatial scales were observed and some gene flow of resistant alleles was indirectly documented in the landscape. A field history index, comprised of additive and weighted WCR management tactics and agronomic practices was developed in an attempt to explain variation in WCR susceptibility. Regression analyses indicated a strong relationship between past management practices and WCR survival on Cry3Bb1, indicating that localized selection pressure is a major contributing factor in determining current susceptibility. These two study areas can be viewed as model systems to draw potential inferences about the relationship of susceptibility to past Bt management histories. These retrospective case histories will inform use of current rootworm-Bt technologies and contribute to the future development of sustainable rootworm management strategies conducted within an IPM framework..
Download or read book Characterization of Western Corn Rootworm coleoptera Chrysomelidae Susceptibility to Foliar Insectivides in Northeast Nebraska written by Timothy B. Dang and published by . This book was released on 2021 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of maize in the United States. A variety of tactics are used to manage this pest such as crop rotation, insecticides, and transgenic maize expressing insecticidal proteins from Bacillus thuringiensis (Bt). WCR populations are highly adaptive and have evolved resistance to these management tactics. Management options are limited as few new tactics are available. Research is needed to evaluate the value of existing tactics used within an integrated framework to manage densities/injury and mitigate resistance. This study evaluated the field performance of formulated foliar insecticides (bifenthrin, chlorpyrifos) targeting adult WCR populations in northeast Nebraska during 2019-2020 with the focus on short and longer-term effects on density. Cohorts of fields were treated with a single application of foliar insecticide or left untreated as controls during the peak adult activity period, then sampled for WCR density before and after treatment. WCR densities, sex ratio, and proportion gravid females were not significantly different in treated and untreated fields prior to insecticide application. Results indicated within-season efficacy of insecticides was excellent as mean adult density was significantly reduced post-application in treated fields compared to control fields. An emergence cage study was conducted the following season to document the effect of foliar insecticides on adult survival. Total adult emergence was significantly reduced the following season in treated fields. Results suggest a single, properly timed insecticide application can reduce build-up of WCR density in continuous maize which would also reduce selection pressure on Bt maize where resistance occurs. A positive relationship between the sampling methods, whole plant counts and unbaited Pherocon AM sticky traps, was derived from the sample data. Susceptibility of adult WCR populations in northeast Nebraska was further characterized by conducting laboratory vial bioassays with bifenthrin, chlorpyrifos, and dimethoate to develop dose-response curves. Results confirmed that the WCR populations were relatively susceptible to the active ingredients with exception of a few populations exhibiting low levels of resistance. These data will serve as a baseline for comparison in future bioassays and inform WCR management programs.
Download or read book Responses of Rotation resistant and Rotation susceptible Populations of the Western Corn Rootworm to Transgenic Corn Expressing Cry Toxins and Validation of a Damage Function for Corn Rootworm Larvae written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interactions Between European Corn Borer Western Corn Rootworm and Three Different Maturing Hybrids of Field Corn written by Daniel Todd Olson and published by . This book was released on 1998 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Western Corn Rootworm Coleoptera Chrysomelidae Diabrotica Virgifera Virgifera LeConte Emergence and Abundance in Transgenic Cornfields with Structured and Seed Blend Refuges written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Western Corn Rootworm Coleoptera Chrysomelidae Host plant Resistance written by Robert J. Knutson and published by . This book was released on 1997 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Impact of Reduced Soil Insecticide Application Rates on Northern and Western Corn Rootworm Coleoptera written by Mark A. Boetel and published by . This book was released on 1996 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biological Control of Corn Rootworms Coleoptera chrysomelidae Using Entomopathogenic Nematodes written by Ann Marie Journey and published by . This book was released on 2003 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
