Progress 10/01/10 to 09/30/15
Outputs
Target Audience:The target audiences for this project are Illinois and Corn Belt corn producers as well as Illinois crop consultants, seed technology/biotechnology professionals, and scientists/students. Outputs derived from this project were used during presentations at the 2015 University of Illinois Agronomy Day, and at a variety of Extension presentations including the 2015 Livingston County Farm Bureau Agronomy Day. Results noted below have also been shared widely through the University of Illinois Pest Management and Crop Development Bulletin. The Bulletin is an online resource that provides timely information about pests and crops throughout Illinois. Changes/Problems:The signature challenge of this project in Illinois has been two fold: 1) There has been the low abundance of Lepidopteran pest species in recent years due to high adoption of Bt corn hybrids and 2) Growing urgency to respond to another maize pest (Bt resistant western corn rootworm) in continuous corn and since 2013 in rotated Bt corn. These circumstances lead to the 2013-2015 shift away from Lepidopteran focus to address a high profile problem with the other pest. The dramatically low abundance of ECB in Illinois will present ongoing challenges to studies of the corn borer; though continuation of ECB surveys in action sites is also a goal. The merged NC-246 group will help to integrate the study of maize pests in a way that make sense for scientists and our constituents. The continuing attrition of Extension faculty at Landgrant institutions like my own presents a more troubling threat to pest studies: there are not enough persons to reasonably cover topics of interest to our constituents. Unless trends are reversed, Extension and applied research will be lost at some universities and grower constituents will have no access to local unbiased information about pest management. What opportunities for training and professional development has the project provided?2013 and 2014 field observations and follow-up 2014 and 2015 Bt resistance bioassay data were part of presentations at the 2013- 2015 University of Illinois Crop Sciences Department Agronomy Day (a large audience (ca. 300-500) of growers, consultants, seed industry professionals and undergraduate/graduate students attended) during late August of each year. Additional presentations at various County Extension Meetings (two during 2013 and 2015 and three during 2014) and corporate-sponsored events that drew in non-corporate audience members (two per year 2013-2015) provided other public forums for raising the issue of resistance among constituents who were eager to report their experiences as well as the developers of the technology. I believe that presenting a coordinated IPM-centered message about resistance in continuous and rotated corn was instrumental in raising awareness about the seriousness of the issue. Though not directly supported on the project, involvement of students and postdocs in ECB surveys and other pest monitoring/bioassay work increased the competency of students (undergraduates and graduates) regarding the chief lepidopteran and coleopteran pests of corn. How have the results been disseminated to communities of interest?Results of the European corn borer surveys were widely disseminated through their appearance in the Bulletin articles from 2014 and 2015. The impact of the changing landscape of Bt trait deployment for single and pyramided Bt traits that target lepidopteran and coleopteran pests (shift toward seed blends and away from block or strip (structured refuges)) has been an important consideration for potential resistance development. The related implications of 'refuge in a bag' as a potential force that could increase the risk for lepidopteran resistance to Bt traits (even as it is seen as a positive force for rootworm resistance management) in corn has been featured in formal and informal discussions with growers and other stakeholders at a variety of corn pest meetings in 2013. Discovery of BT resistance in rotation-resistant WCR overtook lepidopteran concerns in late 2013 until the present (2015); numerous meetings and presentations--especially in the east-central Illinois areas were resistance in rotated corn is problematic--have been popular. WCR resistance in Bt corn was covered in the media via a WILL-AM radio interview for an agricultural program in April of 2015 and an extensive interview recorded in July 2015 in the laboratory and the field for anfeature documentary on resistance by a French film director. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Goal 1: (2013) Field failures of Bt hybrids were documented during 2013. Western corn rootworm (WCR) populations with suspected Bt resistance were collected in 2012 for Bt bioassays in 2013. Populations with suspected resistance to Cry3Bb1 were collected from Mercer, McDonough, and Sangamon counties. WCR were tested on hybrids expressing commercialized rootworm Bt toxins. Suspected Bt resistant populations were bioassayed on only Cry3Bb1 and its isoline. Corrected survival of Bt-susceptible populations on Cry3 Bb1 was low, ranging from 0.068 to 0.250, while that of suspected Cry3Bb1-resistant populations on Cry3Bb1 was high, ranging from 0.797 to 1.350. The Illinois WCR collected from suspected Bt-resistant fields express resistance to the Cry3Bb1 toxin. (2013) In 2013, damage to the roots of Cry3B1-expressing hybrids inLivingston and Kankakee Counties was investigated. Many WCR adults were present along with high populations in adjacent soybean. Adults were collected to obtain eggs for 2014 bioassays. (2014) Bt-resistance bioassays on WCR populations from the 2013 season were completed. Resistance was found to the Cry3Bb1 (YieldGard Rootworm) and mCry3A (Agrisure Rootworm) toxins expressed in Bt hybrids in Livingston and Kankakee County WCR populations from rotated Bt corn. Corrected survival on Cry3Bb1 and mCry3A hybrids was 0.87 and 1.15 for a Livingston County cornfield population and 0.74 and 1.26 for a Kankakee population. Corrected survival in Cry34/35Ab1 hybrids was low (0.03 and 0.16) for the two populations. These results suggest that WCR resistance to Bt can evolve in areas where there is very little continuous corn. (2014) More suspected Bt-resistant WCR populations were collected (two in Livingston County, one in Ford County) from fields that experienced severe corn rootworm injury to rotated Bt corn during 2013. Insects were collected from rotated corn that expressed the Cry3Bb1 toxin (VT3Pro) and from an adjacent soybean field. Eggs were collected for use in single-plant Bt bioassays during 2015. (2015) Historically-excessive rainfall in Illinois during May and June caused periods of saturated soil that destroyed WCR populations. WCR populations were dramatically reduced by flooding that coincided with the period of WCR egg hatch. Adult WCR populations were reduced 10-30 fold compared to previous years. (2015) Single plant Bt-resistance bioassays revealed high levels of WCR resistance to the Cry3Bb1 and mCry3A toxins among WCR collected from rotated corn and soybean fields in Livingston and Ford Counties during 2014. Corrected survival on Cry3Bb1 and mCry3A expressing traits was at or close to 1.0 for all tested populations. Significantly smaller head capsule widths among the surviving larvae from Bt plants indicates that survivors are still affected negatively by the presence of Bt toxins. Additional populations were collected for follow-up bioassays in 2016. Goal 3 and 4: (2014) A European Corn Borer (ECB) survey was conducted during 2013 by a team lead by project Co-PI, Dr. Michael Gray and reported in the University of Illinois Pest Management and Crop Development Bulletin. The (ECB), once a major and consistent insect pest, is now rarely observed in most commercial cornfields. From June 13 to 26, 2014 a research team led by Ron Estes, Principal Research Specialist in Agriculture, and Nicholas Tinsley, Postdoctoral Research Associate, conducted surveys of ECB action sites in the following 12 counties: Champaign (June 13, 5 action sites), Clinton (June 24, 3 action sites), Douglas (June 13, 5 action sites), Fayette (June 24, 4 action sites), Jefferson (June 24, 3 action sites), Kankakee (June 26, 5 action sites), Kendall (June 26, 5 action sites), Knox (June 17, 5 action sites), McLean (June 17, 5 action sites), Pike (June 18, 3 action sites), Sangamon (June 18, 3 action sites), and Whiteside (June 25, 5 action sites). 100 sweeps were taken per action site. Few moths (9 total) were collected: Champaign County - 1 moth, Douglas County - 3 moths (one in each of 3 sites), Kankakee County - 1 moth, Kendall County - 1 moth, Knox County - 1 moth, McLean County - 1 moth, and Sangamon County - 1 moth. In all, 51 action sites (100 sweeps per site) were sampled across 12 counties resulting in 5,100 sweeps that yielded 9 moths, or 0.0018 moths per sweep. 1) Are too few survivors emerging from Bt fields to sustain the continuing efficacy of Bt hybrids against ECB? So far, no field-selected Bt resistant strains of ECB have been documented. 2) Will the growing adoption of smaller (5%) seed-blend refuges for Bt corn hybrids result in even fewer ECB survivors in the landscape and further increase the selection pressure for resistance development? Recall that structured 20% refuges were the norm for Bt corn hybrids for many years. In addition, the structured refuge was a preferred resistance management approach along with the use of high-dose Bt hybrids for ECB. Early on, concern over larval movement from plant to plant by ECB larvae resulted in scientists favoring a structured refuge versus a seed blend for this insect pest. 3) Is the added cost of Bt hybrids worth the investment for this insect pest present at low densities and with low commodity prices? 4) If Bt hybrid use declined, would producers scout large commercial cornfields, utilize economic thresholds, and apply rescue treatments as needed? From "Remember the European Corn Borer?", by M.E. Gray. University of Illinois Pest Management and Crop Development Bulletin. Posted June 30, 2014. (2015) A European Corn Borer (ECB) survey was conducted during 2013, by a team lead by project Co-PI, Dr. M.E. Gray and reported in the University of Illinois Pest Management and Crop Development Bulletin. A University of Illinois Extension IPM Program team lead by Dr. Nick Tinsley (Postdoctoral Research Associate, Department of Crop Sciences) surveyed 28 counties between June 10 to 22 for first-generation ECB injury. The following counties, grouped into six State of Illinois regions, were surveyed: Northwestern Illinois: Bureau, Knox, Mercer, Ogle and Whiteside; Northeastern Illinois: Kane, Kankakee, LaSalle, Livingston and McLean; West-Central Illinois: Adams, Fulton, Logan, McDonough and Morgan; East-Central Illinois: Christian, Clark, Effingham, Piatt and Vermilion; Southwestern Illinois: Bond, Jackson, Macoupin and St. Clair; Southeastern Illinois: Gallatin, Jefferson, Lawrence and Massac. Five cornfields were randomly selected in each county, 100 whorl-stage plants/field were sampled for signs of whorl feeding or the presence of ECB larvae. An action site was sampled for ECB moths near each field by making 100 sweeps with a standard insect sweep net. No ECB moths were recovered at any of the 140 locations in spite of making a total of 14,000 sweeps! Of the 14,000 whorl-stage plants examined, only 68 had shot-holing (evidence of first-generation injury). The mean percentage of plants with first-generation whorl feeding by region was very low: East-Central - 0.28%, Northeast - 0.56%, Northwest - 0.64%, Southwest - 0.75%, Southeast - 0.25%, and West-Central - 0.44%. Extensive use of Bt hybrids and the areawide suppression brought about by these hybrids is the primary explanation for low densities of European corn borers. The stormy weather that enveloped Illinois during the sampling also likely contributed to the poor establishment of the first-generation of ECB. From "Statewide Survey of First-Generation European Corn Borer Confirms Exceedingly Low Population" by Michael E. Gray, University of Illinois Pest Management and Crop Development Bulletin. Posted July 14, 2015. Full report is accessible at: http://bulletin.ipm.illinois.edu/?p=3339. Goal4: (2013-2015) Sharing of research findings from the 2014/2015 surveys of ECB in action sites and 2013-2015 findings from Bt-resistance bioassays via the University of Illinois' Pest Management and Crop Development Bulletin.
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: The target audiences for this project are Illinois and Corn Belt corn producers as well as Illinois crop consultants, seed technology/biotechnology professionals, and scientists/students. Outputs derived from this project were used during presentations at the 2013 University of Illinois Agronomy Day, and at a variety of Extension presentations including the 2014 Livingston County Farm Bureau Agronomy Day and the NIREC Corn Rootworm Session. Results noted below have also been shared widely through the University of Illinois Pest Management and Crop Development Bulletin. The Bulletin is an online resource that provides timely information about pests and crops throughout Illinois. Changes/Problems: As described in the accomplishments, low abundance of target Lepidopteran species and urgent needs to respond to another maize pest (Bt resistant western corn rootworm) lead to a 2013-2014 shift away from Lepidopteran focus to address a high profile problem with the other pest. The dramatically low abundance of ECB in Illinois will present ongoing challenges to studies of the corn borer; continuation of ECB surveys in action sites is also a goal. What opportunities for training and professional development has the project provided? 2013 field observations and follow-up 2014 Bt resistance bioassay datawere part of a presentation at the 2014 University of Illinois Crop Sciences Department Agronomy Day (audience of growers, consultants, seed industry professionals and undergraduate/graduate students) during late August. Additional presentations at various Extension and corporate-sponsored events provided an even broader public forum for raising the issue of resistance among a group of constituents who were eager to report their experiences; I believe that presenting a coordinated IPM-centered message about resistance in continuous corn, was instrumental in raising awareness about the seriousness of the issue. How have the results been disseminated to communities of interest? Results of the European corn borer survey were widely disseminated through their appearance in the June 30, 2014 Bulletin article. The implications of ‘refuge in a bag’ as a potential force that could increase the risk for lepidopteran resistance to Bt traits in corn has been featured in formal and informal discussions with growers and other stakeholders at a variety of corn pest meetings. Bt resistance and WCR bioassay methods and results were part of a presentation at the 2014 University of Illinois Crop Sciences Department Agronomy Day (audience of growers, consultants, seed industry professionals and undergraduate/graduate students) during late August. Later interactions with growers, consultants, and multiple interviews with persons from the media have increased awareness of resistance in continuous and rotated corn as well as the WCR as a pest insect that is active in both corn and soybean fields. Findings about Bt resistance in rotated cornfields were presented at several local and regional meetings that included emphases on resistance and IRM. What do you plan to do during the next reporting period to accomplish the goals? In the coming reporting period, NC-205 will merge with the NCCC-046 (Development, Optimization, and Delivery of Management Strategies for Corn Rootworms and Other Below-Ground Insect Pests of Maize) to form a combined group, NC-246. The merger reflects the wisdom and efficiency of focusing on the complex of pests that threaten the same host plants. The merged committee will address delivery and management strategies for above and below ground pests of corn; integration of out efforts is anticipated to improve our research scope and relevance. Multiple presentations are planned for constituents throughout NE, E and East-Central Illinois (areas of heavy corn product) to review the concept of resistance and the importance of adopting a more integrated approach to IPM for both lepidopteran and corn rootworm pests of corn in 2015. ECB and other lepidopteran corn pests are a challenge to work with in east-central Illinois due to low population abundances. I will modify my plans for monitoring to widen my research net to a species for which populations are more reliable, such as the corn earworm, Helicoverpa zea, which migrates into the state. I would like to conduct some intrafield movement studies of adults and larvae.
Impacts
What was accomplished under these goals?
1. Investigate the relationship between transgenic maize and the agricultural environment. This goal was addressed by surveys of ECB in action sites and quantification of Bt-resistance in pests from rotated corn and soybean fields. 2. Adapt IPM systems for the changing pest complexes in maize. No adaptions to report. 3. Investigate ecology, evolution, genetics, and behavior of pest Lepidoptera. Survey of ECB in action sites addressed this investigative goal. 4. Employ electronic delivery methods to disseminate information related to sustainable management of Lepidopteran pests. Sharing of findings from the survey of ECB in action sites and findings from Bt-resistance bioassays via the University of Illinois’ Pest Management and Crop Development Bulletin was one action that helped to reach this goal.
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Progress 10/01/12 to 09/30/13
Outputs
Target Audience: The target audiences for this project are Corn Belt corn producers as well as Illinois crop consultants, seed technology/biotechnology professionals, and scientists/students. Outputs derived from this project were used during presentations at the 2013 University of Illinois Agronomy Day, the Wilson Fertilizer Inc. Grower Conference, and the Pioneer Hi-Bred, Heartland Agronomy Conference; these audiences specifically included local growers as well as science/research professionals, university students, Extension personnel, and representatives of agricultural biotechnology companies. Changes/Problems: As described, problems with target species abundance and urgent needs to respond to another maize pest lead to a shift away from Lepidopteran focus to address a high profile problem with another pest of maize, the western corn rootworm. What opportunities for training and professional development has the project provided? 2013 Bioassay data were part of a presentation at the 2013 University of Illinois Crop Sciences Department Agronomy Day (audience of growers, consultants, seed industry professionals and undergraduate/graduate students) during late August that lead to the reports of suspected WCR Bt resistance in rotated corn directed at University of Illinois researchers and extension professionals. Presenting those data in a large public forum raised the issue of resistance among a group of constituents who were eager to report their experiences; I believe that presenting a coordinated IPM-centered message about resistance in continuous corn, was instrumental in raising awareness about the seriousness of the issue--it got people talking. Follow-up with some growers and consultants, as well as interviews with local media have been just the beginning of training and dissemination of the IPM message regarding Bt resistance in rotated corn. How have the results been disseminated to communities of interest? In 2013 monitoring data was part of a presentation at the 2013 University of Illinois Crop Sciences Department Agronomy Day (audience of growers, consultants, seed industry professionals and undergraduate/graduate students) during late August. Later interactions with growers, consultants, and mutliple interviews with persons from the media have increased awareness of resistance in continuous and rotated corn as well as the WCR as a pest insect that is active in both corn and soybean fields. Findings about apparent Bt resistance in rotated cornfields were presented at a technical conference focused on pest resistance modeling. Several workshops have been schedued to discuss resistance in the coming months. What do you plan to do during the next reporting period to accomplish the goals? Multiple presentations are planned throughout NE, E and East Central Illinois (areas of heavy corn and soybean crop rotation) to re-acquaint constituents with the concept of resistance and why refuge is important--especially for low dose Cry events (all Cry proteins that target WCR are not expressed at a high dose level, while Lepidopteran Cry proteins are all high dose events). In 2014, I will modify my plans for montoring to widen my research net to a species for which populations are more reliable, such as the corn earworm, Helicoverpa zea, which migrates into the state (less impact of locally extreme conditions on populations) and has been the subject of successful fieldwork on the campus in recent years (see UI Crop Sciences “On Target” publication: https://ipm.illinois.edu/ontarget/). I would like to conduct some intrafield movement studies of adults and larvae.
Impacts
What was accomplished under these goals?
Though the lepidopteran pest populations in corn did not reach levels where study was possible; the related and relevant question of whether a transgenic maize hybrid can fail in the field was documented during the 2013 season. Multiple western corn rootworm populations with suspected resistance to Bt corn were collected during the summer of 2012 and prepared for bioassays planned for early 2013. Ag Expt. Station funding provided growth chambers, I leveraged that funding to fund construction of Berlese funnels and to secure materials and supplies to begin bioassay of three WCR populations with suspected resistance to Cry3Bb1-expressing Bt corn in June of 2013. Suspected resistant populations were obtained with cooperation of Monsanto Technical representatives from fields with unexpected levels of corn rootworm damage to the roots of Bt corn hybrids expressing the Cry3Bb1 toxin. Populations were collected from Mercer (“Frieden”), McDonough (“Waller”), and Sangamon (“Bruntjen”) counties. Bt susceptible populations (“Penn#2”, “Clay Center”, and “Meade”) with no exposure to Bt toxins (all were field collected prior to commercialization of Bt corn) were obtained from the USDA-NCARL laboratory in Brookings, SD. Bt bioassay procedures followed the methods of Gassmann et al. (2011) (Gassmann AJ, Petzold-Maxwell JL, Keweshan RS, Dunbar MW, 2011). Field-evolved resistance to Bt maize by western corn rootworm. PLOS ONE 6: e22629.) Populations were tested on corn hybrids expressing one of each commercialized rootworm Bt toxin (Cry3Bb1, Cry34/35Ab1 and mCry3A) along with a genetically similar near-isoline that did not express the Bt toxin. Comparisons (i.e. corrected larval survival) were based on corrected larval survival on Bt corn by the suspected resistant population vs. mean corrected larval survival on Bt corn among Bt susceptible populations. Resistance ratios were also calculated. Due to limited larval availability suspected Bt resistant populations were bioassayed on only Cry3Bb1 and its isoline (“Freiden” was tested also on mCry3A and its isoline); Bt susceptible populations were bioassayed on all three Bt toxins and their isolines. Over 350 replicates were completed before mounting egg mortality due to prolonged storage halted the assays. Corrected survival of Bt-susceptible populations on Cry3 Bb1 was low, ranging from 0.068 to 0.250 (mean corrected survival was 0.156). Corrected survival of suspected Cry3Bb1-resistant populations on Cry3Bb1 was high, ranging from 0.797 to 1.350 (more larvae survived on the Cry3Bb1 hybrid than on the non-Bt isoline!). Resistance ratios ranged from 5.1x to 8.7x the resistance level of control populations. These data indicate that all three populations of Illinois WCR collected from suspected Bt-resistant are likely expressing field-evolved resistance to the Cry3Bb1 toxin. The “Freiden” population had a corrected survival on mCry3A corn of 0.839, suggesting that it resistance to Cry3Bb1 may endow a population with cross-resistance to the structurally similar mCry3A toxin. In mid-August, I was alerted to the presence of unexpected levels of corn rootworm injury to the roots of Cry3B1-expressing corn roots in multiple rotated cornfields in Livingston and Kankakee Counties (Illinois); in mid-September, I was notified of additional injury in a Ford County cornfield. Extremely high populations of WCR adults were present in these cornfields and there were also high populations of adults (majority females) in adjacent soybean fields nearing 100 WCR adults per 100 sweeps. Thousands of adults were collected from two cornfield populations and one soybean field population. They were to used to obtain eggs for future bioassays throughout the fall. Approximately 1 million eggs are now in storage and will be ready for bioassay in February 2014.
Publications
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