SUSTAINABILITY OF SWEET CORN IPM: TRANSGENIC HYBRIDS, INVASIVE SPECIES & BIOLOGICAL CONTROL

• Sponsoring Institution: State Agricultural Experiment Station
• Project Status: COMPLETE
• Funding Source: STATE
• Reporting Frequency: Annual
• Accession No.: 1003159
• Project Start Date: Jul 1, 2014
• Project End Date: Jun 30, 2019
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108

Performing Department
Entomology

Non Technical Summary
As of 2011, sweet corn contributed a farm-gate value of approx. $96 million each year to Minnesota's agricultural economy (Minnesota Agricultural Statistics 2012). Total annual production over the last 5 years has averaged approximately 130,000 acres for processing ($65-105 M) and 8,000 acres ($35-50 M) for fresh market. In addition, processing sweet corn is typically contracted with corn and soybean growers, providing added diversification to much of southern Minnesota. The farm-gate value for processing sweet corn does not include the additional 4-fold increase in retail value of final marketable product. With all major processing companies operating in Minnesota, Wisconsin, and Illinois, the industry also creates significant regional value, with nearly 45% of U.S. processing sweet corn produced in these three states. In addition to the initial releases of sweet corn hybrids expressing Bacillus thuringiensis (Bt) proteins with insecticidal activity on lepidopteran larvae, over the past 5 years, the sweet corn seed industry has added the release of multiple new Bt events for sweet corn integrated pest management (IPM). These hybrids contain Bt proteins with selective specificity against multiple lepidopteran pests. The primary pests targeted by Bt sweet corn include Ostrinia nubilalis, European corn borer (ECB), and Helicoverpa zea, corn earworm (CEW).Most Bt corn hybrids expressing the Cry1Ab insecticidal protein, provide 99-100% control of ECB and 80-95% control of CEW without the use of insecticides. To continue providing effective control of ECB and CEW, and expand the pest spectrum, seed companies developed several alternative Bt traits that are now commercialized. This pyramiding of events provides better control of targeted pests and should minimize the risk of resistance development. Although the value of Bt hybrids is clear high, societal concerns about the safety of Bt crops worldwide, has limited the use of Bt sweet corn; thus, the Bt sweet corn has been adopted primarily by fresh-market growers, with few processing companies using the technology. Consequently, there is continued emphasis on conventional insecticide use, while also limiting the risk of insect damage and contaminants in final product. The primary approach for the industry is to continue to expand the use of an IPM approach, where all feasible control methods are implemented. This also allows for consideration of how to deal with new and invasive pest species that may arrive in the U.S. Of particular concern is the recent detection of Helicoverpa armigera in Brazil (e.g., http://agfax.com/2014/01/09/concerns-brazilian-cotton-soybean-pest-reach-u-s/ ; Hutchison et al. 2014). Efficacy of sweet corn expressing Bt insecticidal proteins has been shown over time to range from 99-100% control for ECB (Burkness et al. 2001, Burkness et al. 2002, Hutchison et al. 2010). However, for CEW, efficacy results have not achieved such high levels and remains between 80-95% control in most cases (Burkness et al. 2010, Shelton et al. 2013). Because CEW does not overwinter in Minnesota and is exposed to various pest management strategies in the southern U.S. where migrants originate from, the development of both insecticide resistance (Hutchison et al. 2007) and resistance to Bt proteins has been a concern. To provide a way to quantify this risk, we place a premium on monitoring for resistance levels to both insecticides and Bt insecticidal proteins in the migrants encountered in Minnesota via the use of sentinel plots (also referred to as the "in-field screen"). Moreover, sentinel plots also allow us to monitor for the potential arrival of the invasive pest H. armigera. Helicoverpa armigera is a potential new pest that would further add to the difficulty of managing lepidopteran pests in sweet corn. Biologically and ecologically, this species is also quite similar to H. zea; however, H. armigera is apparently more damaging on "per capita" basis, e.g., on corn and soybeans. As of 2013, H. armigera had been detected in Brazil and had already been estimated to have caused over 900 M in crop loss. Venette et al. (2003) conducted a risk assessment which indicated that the upper Midwest and Minnesota specifically would provide a suitable habitat for establishment of H. armigera. In addition, between 1985 and 2000, H. armigera was intercepted over 4,400 times at ports of entry to the U.S. (Venette et al. 2003), suggesting the risk for H. armigera entering the country and becoming established is high. If H. armigera does become established, the current population dynamics and patterns of migration present with H. zea, provides a window into what the expected dispersal and impact might be for H. armigera. With a much greater potential for the development of insecticide resistance and crop injury, H. armigera establishment could add considerable cost to sweet corn production. To provide a reliable way to collect data and monitor for the presence of H. armigera, pheromone traps (baited with synthetic sex pheromone) will be used to attract H. armigera male moths (Kehat et al 1982). If moths are captured in the pheromone traps, positive identification can be made using diagnostic characters of the male genitalia (Pogue 2004). In addition to monitoring resistance levels in pests of sweet corn, we are also interested in evaluating and developing novel pest management approaches for sweet corn (Burkness et al. 2009, Burkness et al. 2010). Novel approaches will include evaluations of new reduced-risk insecticide active ingredients, spray timings, and sweet corn hybrids expressing new Bt proteins. As these new pest management options come online, close attention will be paid to resistance management strategies (Burkness et al. 2011, Burkness and Hutchison 2012) and further support the use of and need for resistance monitoring via sentinel plots. Another novel approach under consideration is the use of small plantings of sweet corn. This approach has been implemented successfully by Rhino et al. (2014) to protect tomato from H. zea using a sweet corn trap crop. We believe this can be further enhanced using an attractant developed in Australia for H. armigera in cotton, known as Magnet. This lure, which is composed of a blend of floral volatiles, may be used with an insecticide to also provide adult moth control and reduce oviposition. This has the added benefit of being attractive to both H. armigera and H. zea and therefore, will be a useful control strategy to develop in light of potential H. armigera invasions. In an attempt to augment any new or existing management strategies, we will examine the role of generalist predators such as Orius spp. in reducing populations of H. zea in sweet corn. Several studies have demonstrated that transgenic corn expressing Bt proteins has little effect on generalist predator populations under field conditions (Wold et al. 2001, Tian et al. 2014). We will quantify the impact that these predators may have on H. zea. We also have preliminary data, based on DNA markers, confirming Orius predation on H. zea eggs in Minnesota (J. Peterson et al., unpublished). Our proposed research will continue to document predation levels on H. zea. In addition, to quantify Orius spp. population densities, we will develop a practical sampling plan for Orius spp. adults and nymphs in sweet corn, similar to previous sampling plans developed for arthropods in sweet corn (Koch et al. 2006, Paula-Moraes et al. 2011). In addition, the impact of Orius spp. on pests could be further quantified by determining the ability of Orius to consume H. zea eggs or early instars that have fed on Bt corn tissue (e.g., Dutra et al. 2012, Tian et al. 2014). As the results from these complementary objectives are incorporated into IPM programs, we are confident that a substantial contribution will be made towards achieving more sustainable sweet corn production in Minnesota.

Animal Health Component

90%

Research Effort Categories

Basic

10%

Applied

90%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
211	3110	1130	100%

Knowledge Area
211 - Insects, Mites, and Other Arthropods Affecting Plants;

Subject Of Investigation
3110 - Insects;

Field Of Science
1130 - Entomology and acarology;

Keywords

sweet corn

ipm

transgenic hybrids

invasive species

biological control

Goals / Objectives
1) Sentinel plots for resistance monitoring of H. zea and O. nubilalisa. Annual insecticide efficacy trial - small plotb. Field corn planted every 2 weeks starting at May 1st until June 30th with non-Bt hybrid and Bt hybrids containing Smartstax and Viptera events2) Sweet corn as a trap crop with "push-pull" strategya. Through planting date and variety manipulation create attractive planting of sweet corn around larger sweet corn field for H. zeab. In addition to creating attractive trap crop, use of Magnet attractant and insecticide to manage adult population of H. zea moths3) Impact of Orius spp. on populations of H. zea in sweet corna. Quantify H. zea egg consumption - cage studies & molecular confirmationb. Develop a sequential sampling plan for Orius adults4) Potential, high-risk, invasive species: Helicoverpa armigera a. Multistate monitoring in the Midwest and South using pheromone trapsb. Testing H. armigera pheromone lure(s) for host specificityc. Determine consistent and reliable method for adult identification of H. armigera vs. H. zea

Project Methods
1) Establish sentinel plots for resistance monitoring of H. zea and O. nubilalis to Bt proteins expressed in transgenic corn hybrids. Insecticide efficacy trials will be setup as 2 row plots that are 25ft in length with 4 replications in a randomized complete block design. Field corn sentinel plots containing the Smartstax® and Viptera® events will be established at the Rosemount Experiment Station, Rosemount, MN, every 2 weeks starting May 1st and concluding on June 30th. Plots will consist of 4 rows that are 50 ft long. A non-transgenic plot will be planted at the same time to provide an overall indication of background populations of each pest. The Smartstax® and Viptera® events were selected to represent the majority of Bt proteins that will be present in both transgenic field corn and sweet corn. When ears reach the R3-R4 stage, before kernels begin to dent, 100 primary ears will be harvested from the sentinel plots and rated for the species present, larval instar, and associated damage. The sentinel plots will also be used in conjunction with pheromone trapping to establish the presence or absence of H. armigera in Minnesota. 2) Evaluate the use of sweet corn as a trap crop, combined with a push-pull strategy to manage H. zea in sweet corn. The trap crop will consist of 8 rows of sweet corn planted on either side of a larger field of sweet corn. This plot setup will be replicated at least 3 times. The trap crop will be planted to achieve the silking stage (R1) approximately 1-2 weeks prior to when the main crop will be at R1. This will be accomplished through a combination of planting date and hybrid selection based on relative days to maturity. The earlier silking in the trap crop should serve as an attractant for H. zea and provide the "pull" component of the push-pull strategy. 3) Assess the potential of generalist predators to provide biological control of H. zea in sweet corn, and to assist in mitigating the risk of Bt resistance in H. zea. We propose using cage studies to combine known numbers of Orius spp. with known numbers of H. zea eggs on primary sweet corn ears to assess the impact Orius spp. feeding may have on H. zea populations. This research will be conducted in a field, arranged with 4 replications and a randomized complete block design. In addition to egg counts at 24- and 48-hr post-infestation with Orius, we will collect Orius to return to the lab for DNA analysis of H. zea, to confirm the proportion of Orius feeding on the pest. In addition to the predation research, we will develop and validate a new sequential sampling plan to estimate Orius spp. populations more efficiently in sweet corn. Data will be collected from sweet corn fields using the primary ear as the sample unit and a fixed sample size of 50 primary ears per field on each sample date. The sampling data will then be used to generate a fixed precision enumerative sequential sampling plan, and validated using Resampling Validation of Sampling Plans (RVSP) approach (e.g., Koch et al. 2006).4) Establish a monitoring network for Helicoverpa armigera in the Southern and Midwestern United States.. Through the use of sex pheromones and pheromone traps, and light traps, cooperators will be established in the southern (e.g., Southeast, Mid-south, Texas, and Southwest) US to detect early invasions that may occur through active migration of H. armigera from established populations currently residing in Brazil/S. America. In addition, traps would be established in the Midwestern (e.g., Minnesota, Illinois, and Wisconsin) US to track early invasions as it is likely H. armigera would migrate south-north each year, on Low-level jets (LLJs), in a similar fashion as H. zea. The efficacy of pheromone traps, or more accurately, the specificity of the pheromone traps will need to be verified because of the close relationship between H. armigera and H. zea. Therefore, it is necessary to develop an accurate method for field identifying any moths captured in the pheromone traps. Currently, H. armigera and H. zea moths are distinguished using characteristics of the male genitalia. In addition to taxonomic characters for identification, new identification methods such as polymerase chain reaction (PCR) or infield enzyme-linked immunosorbent assay (ELISA) tests could be evaluated. Pheromone lures for H. armigera and H. zea are commercially available from Hercon™ and Scentry™. Traps in the South and Midwest would be set up and monitored during the main growing season.

Progress 07/01/14 to 06/30/19

Outputs
Target Audience:The primary target audiences include the fresh-market sweet corn and snap bean growers (MN Fruit & Veg. Growers Assoc., and Minn. Dept of Agric., "MN Grown"),as well as pest managers within the Midwest Food Processors Assoc. (3-state region: MN, WI, IL),. In addition, the Ag Professionals and Crop Consultants and MN Extension educator staff, advising field corn growers, are key target audiences of the researcch results as well. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?In addition to part-time effort byundergraduate and graduate students, a research scientist, along with a post-doctoral associate have also been assisting with this project. In so doing, they have each obtained valuable field experience in conducting surveys for two important corn insect pests (H. zea, and O. nubilalis), and knowledge regarding how to conduct the in-field screen for Bt resistance monitoring. Post-doctoral associates (Deans, Cira) also contributed to selected publications. How have the results been disseminated to communities of interest?During 2015-2019, throughout the project, we have posted weekly moth flight (trap catch) network data for both H. zea and O. nubilalis, on the VegEdge web site (www.vegedge.umn.edu). The primary audience for pest data inlcudes agric. professionals, crop consultants, and some of the fresh market farmers, including vegetable and organic growers. Web page data is also referred to in articles on the Crop e-News, which has >1700 subscribers. The information is also disseminated by an SW MN, regional IPM Specialist, who has >1000 subscribers to his crop pest newsletter and his twitter account. Annual moth flight pressure, and resistance monitoring information are also delivered to sweet corn processing company representatives, at the annual Midwest Food Products Assoc. meetings in November each year; in 2018, this included approx. 120 MWFPA professionals. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? 1. Sentinel plots for resistance monitoring of H. zea and O. nubilalis: a) Annual insecticide efficacy trial - small plot: The purpose of this objective is to continue to evaluate the efficacy of insecticides against European corn borer (ECB, Ostrinia nubilalis) and the efficay or resistance status of corn earworm (CEW, Helicoverpa zea) to pyrethroids. Each year, a comprehensive insecticide trial was conducted for the project, and again in 2018 at the Rosemount Exp. Stn., near Rosemount, MN. A new positive trend detected in both 2017 and 2018, is that several pyrethroid insecticides provided >90%control of CEW in sweet corn. These results of the past two years indicate that at least some level of pyrethroid susceptibility in CEW populations has returned, allowing for more acceptable levels of control. Given the results for the past two years, we consulted with entomologists at Texas A&M University, regarding current insecticidal control patterns by growers in TX, whereH. zea moths are most likely to originate, before migrating north to MN each summer. They confirmed that pyrethroid use had been reduced substantially due to their previous issues with resistance in cotton and vegetable crops. The increased use of diamides (e.g., Coragen) in TX, and/or nearby states, likely reduced the pyrethroid selection pressure in TX, and subsequently reduced the frequency of resistance genes in the CEW populations migrating north. Additonal Adutl Vial Test (AVT) assays for adult susceptibility to pyrethroids in 2018 confirmed only a moderat level of resistant moths (~ 15% survival), when exposed to the standard cypermethrin. Because of grower concerns, this research will continue in the near future. CEW flights in late August - Sept., continue to be substantial, with final larval infestations in non-insecticide treated plots averaging 1.60, 0.78 and 0.49 larvae/ear, for 2016-2018. Not surprisingly, ECB larvae are rarely detectetd at the Rosemount location in non-Bt corn. This trend for historically low populations is attributed to the continued efficacy of transgenic, Bt field corn use in MN.b) Sentinel Plots:Each year of the project, sentinel sweet and field corn was planted every 2 weeks starting at May 1st until June 30th with non- Bt hybrids, and Bt hybrids containing Smartstax and Viptera events. The purpose of these plots was to essentially serve as an "In-field screen" for field level resistance monitoring of CEW and ECB, to potential resistance to one or more Bt events. Both Bt and non-Bt field corn and sweet corn hybrids were planted each year, covering a range of transgenic events (Cry1Ab, Vip3a, and Cry1F) for control of Lepidopteran pests in corn. Five planting dates were established and only the field and sweet corn hybrid expressing Vip3a provided complete control of CEW; this was consistent for the past 4 years, including 2018.Again, ECB was not detected in any planting date or hybrid for most of the past 4 years. The last planting date of the non-Bt hybrid Providence had a peak CEW density of 0.65 larvae per ear. These results provide ongoing value to sweet corn growers, confirming a low risk of O. nubilalis at this location in MN, and by contrast, the planting dates that continue to be at high-risk to H. zea.A significant outcome of the research, is that we confirmed a high level of CEW resistance to the Cry1Ab, Bt protein (2016- 2018), under field conditions. For example, for 2016-2017, we observed 100% control of CEW larvae in Vip3a sweet corn ears (known high-dose, combined ith Cry1Ab). However, with the Cry1Ab event alone, we found 0.0% control, and actually higher numbers of larvae per ear (2.3 in 2016; 0.89 in 2017) compared to the untreated non-Bt ears (1.60 in 2016; 0.78 in 2017). These results provide evidence of resistant phenotypes via low/zero efficacy by Cry1Ab, but also illustrate the value of using Bt and non-Bt sweet corn as an "In-field screen" for early detection of resistance. 2. Sweet corn as a trap crop with push-pull strategy: a) Through planting date and variety manipulation create attractive plantings of sweet corn around a larger sweet corn field for H zea: We identified at-risk planting and harvest dates for CEW, which are later than June 10th and August 31st, respectively. We evaluated several attractants and identified a potential mixture of molasses and Rimon (an insect growth regulator) that holds promise for use in a push pull system. However, after 3 years of research, we found that the treatments did not provide consistent results. b) In addition to creating attractive trap crop, use of Magnet attractant and insecticide to manage adult population of H. zea moths; After 3 years of research, we have determined that the use of an attractant like Magnet will only provide a significant added level of control when pyrethroid resistance is present in the current years' H. zea population, which is variable year to year as moths migrate into MN each season. Therefore, we began to asses the use of molasses (less expensive alternative to Magnet) in combination with Rimon, an insect growth regulator, that should effect moths fecundity regardless of the insecticide resistance status of exposed moths. Data from 2017 suggests that H. zea populations were susceptible to pyrethroids (higher level of susceptibility vs2015-2016). Treated small plots had a per ear density of 0.05 and treated large plots had a density of 0.01 per ear. Untreated check plots were at 0.26 H. zea per ear. However, given our results, and the cost of treatment, we do not believe this strategy will be cost-effective; this project was terminated in 2018. 3. Impact of Orius spp. on populations of H. zea in sweet corn: a) Quantify H. zea egg consumption - cage studies & molecular confirmation: Methods were developed for obtaining reliable estimates of Orius spp. predation on CEW eggs under field conditions were developed, focusing on the tassel to silking stages of sweet corn. Orius adults and nymphs have been consistently abundant (0.5 to >3 per ear), when focusing on ears that are 7-21 days in age. Results from the molecular study was completed and published his year (Peterson et al. 2018). b) Develop a sequential sampling plan for Oriusadults; Additional data sets for Orius spp. were collected from sweet corn plots at the Rosemount ROC in 2018 over a range of planting dates and growth stages. Data sets for sample plan development were collected using a sample unit of the primary ear on a single sweet corn plant and a sample size of 30 ears. This analysis will be completed using Resampling for Validation of Sampling Programs (RVSP) software, developed by WD Hutchison and SE Naranjo. 4. Potential, high-risk, invasive species: Helicoverpa armigera: a) Multistate monitoring in the Midwest using pheromone traps.This project was terminated in 2018, due to a lack of H. armigera moth detections in MN during the previous 3 years of monitoring. This effort included additoinal monitoring by staff with the MDA, and via collaborations with the Wisconsin Dept. of Agric. as well. In brief, since the beginning of the project, the current pheromone lures commercially available for H. armigera have not improved. This resulted in excess H. zea moths captured in traps baited with the H. armigera lure, and in manycases hundreds of H. zea moths captured. High captures of H. zea is very in-efficient in that all moths must still be dissected, and male genetalia carefully examined, to distinguish the two species. Also, next gen. sequencing tools are still not ready for field use; this should eventually allow for rapid identification of the two species, and the zea x armigera hybrid that can also occur. Given these obstacles, the project was terminated after the 2017 season.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Peterson, J. A., E. C. Burkness, J. D. Harwood, and W. D. Hutchison. 2018. Molecular gut-content analysis reveals a strong trophic connection between the insidious flower bug Orius insidiosus and corn earworm Helicoverpa zea in sweet corn. Biological Control. 121:1-7, DOI: 10.1016/j.biocontrol.2018.02.006
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Dively, G.P., P.D. Venugopal, D. Bean, J. Whalen, K. Holmstrom, T.P. Kuhar, H.B. Doughty, T. Patton, W. Cissel, & W.D. Hutchison. 2018. Regional pest suppression associated with widespread Bt maize adoption benefits vegetable growers. Proc. National Acad. Sciences (PNAS). 115(13): 3320-3325.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Deans, C.A., Sword, G.A., Lenhart, P. A., Burkness, E., Hutchison, W.D., Behmer, S.T. 2018. Quantifying Plant Soluble Protein and Digestible Carbohydrate Content, Using Corn (Zea mays) As an Exemplar. J. Vis. Exp. (138), e58164, doi:10.3791/58164
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Svobodov�, Z., E. C. Burkness, O. Skokov� Habuatov�, & W. D. Hutchison. 2017. Predator preference for Bt-fed Spodoptera frugiperda (Lepidoptera: Noctuidae) prey: Implications for insect resistance management in Bt maize seed blends. J. Econ. Entomol. 110(3): 1317-1325
• Type: Other Status: Published Year Published: 2018 Citation: Burkness, E.C., S.J. Wold, and W.D. Hutchison 2018. Insecticidal control of lepidopteran pests in sweet corn, 2017. Arthropod Management Tests. 43: DOI: 10.1093/amt/tsy005
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Milne, A.E., J.R. Bell, W.D. Hutchison, F. van den Bosch, P.D. Mitchell, D. Crowder, et al. 2015. The effect of farmers decisions on pest control with Bt crops: A billion dollar game of strategy. PLoS Comput. Biol. 11(12): e1004483.
• Type: Book Chapters Status: Published Year Published: 2017 Citation: Hutchison, W.D. & T.M. Cira. 2017. Economically important maize insect pests, pp. 263-292. In: Watson, D. (ed.) Achieving sustainable cultivation of maize Vol. 2: Cultivation techniques, pest and disease control. Burleigh Dodds Science Publishing, Cambridge, UK. (ISBN: 978 1 78676 012 8).
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Kriticos, D. J., N. Ota, W.D. Hutchison, J. Beddow, T. Walsh, et al. 2015. The potential distribution of invading Helicoverpa armigera in North America: Is it just a matter of time? PLoS ONE 10(3): e0119618. doi: 10.1371/journal.pone.0119618

Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Fresh-market sweet corn and snap bean growers (e.g, with MN Grown, and MN Fruit & Veg. Growers Assoc.), as well as pest managers within the Midwest Food Processors Assoc. (3-state region: MN, WI, IL). In addition, the Ag Professionals and Crop Consultants and MN Extension field staff, advising field corn growers, are key target audiences as well. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?In addition to part-time effort by both undergraduate and graduate students, a research scientist, along with a post-doctoral associate have also been assisting with this project. In so doing, they have each obtained valuable field experience in conduciting surveys for two important corn insect pests (H. zea, and O. nubilalis), and knowledge regarding how to conduct the in-field screen for Bt resistance monitoring. How have the results been disseminated to communities of interest?During 2018 (and as in previoius years), we posted weekly moth flight (trap catch) network data for both H. zea and O. nubilalis, on the VegEdge web site (www.vegedge.umn.edu). The primary audience for pest data inlcudes agric. professionals, crop consultants, and some of the fresh market farmers, including vegetable and organic growers. Web page data is also referred to in articles on the Crop e-News, which has >1700 subscribers. The information is also disseminated by an SW MN, regional IPM Specialist, who has >1000 subscribers to his crop pest newsletter and his twitter account. Annual moth flight pressure, and resistance monitoring information are also delivered to sweet corn processing company representatives, at the annual Midwest Food Products Assoc. meetings in November each year; in 2018, this included approx. 120 MWFPA professionals What do you plan to do during the next reporting period to accomplish the goals?We will continue to complete the same research objectives for 2019, and disseminate the results, via the MN Extension IPM Program, educaitonal events, and vegedge web site.

Impacts
What was accomplished under these goals? Sentinel plots for resistance monitoring of H. zea and O. nubilalis: a) Annual insecticide efficacy trial - small plot: The purpose of this objective is to continue to evaluate the efficacy of insecticides against European corn borer (ECB, Ostrinia nubilalis) and the efficay or resistance status of corn earworm (CEW, Helicoverpa zea) to pyrethroids. Each year, a comprehensive insecticide trial was conducted for the project, and again in 2018 at the Rosemount Exp. Stn., near Rosemount, MN. A new positive trend detected in both 2017 and 2018, is that several pyrethroid insecticides provided >90% control of CEW in sweet corn. These results of the past two years indicate that at least some level of pyrethroid susceptibility in CEW populations has returned, allowing for more acceptable levels of control. Given the results for the past two years, we consulted with entomologists at Texas A&M University, regarding current insecticidal control patterns by growers in TX, whereH. zea moths are most likely to originate, before migrating north to MN each summer. They confirmed that pyrethroid use had been reduced substantially due to their previous issues with resistance in cotton and vegetable crops. The increased use ofdiamides (e.g., Coragen) in TX, and/or nearby states, likely reduced the pyrethroid selection pressure in TX, and subsequently reduced the frequency of resistance genes in the CEW populations migrating north. Additonal Adutl Vial Test (AVT) assays for adult susceptibility to pyrethroids in 2018 confirmed only a moderat level of resistant moths (~ 15% survival), when exposed to the standard cypermethrin. Because of grower concerns, this research will continue in the near future. CEW flights in late August - Sept., continue to be substantial, with final larval infestations in non-insecticide treated plots averaging 1.60, 0.78 and 0.49 larvae/ear, for 2016-2018. Not surprisingly, ECB larvae are rarely detectetd at the Rosemount location in non-Bt corn. This trend for historically low populations is attributed to the continued efficacy of transgenic, Bt field corn use in MN. b) Sentinel Plots:Each year of the project, sentinel sweet and field corn was planted every 2 weeks starting at May 1st until June 30th with non- Bt hybrids, and Bt hybrids containing Smartstax and Viptera events. The purpose of these plots was to essentially serve as an "In-field screen" for field level resistance monitoring of CEW and ECB, to potential resistance to one or more Bt events. Both Bt and non-Bt field corn and sweet corn hybrids were planted each year, covering a range of transgenic events (Cry1Ab, Vip3a, and Cry1F) for control of Lepidopteran pests in corn. Five planting dates were established and only the field and sweet corn hybrid expressing Vip3a provided complete control of CEW; this was consistent for the past 4 years, including 2018.Again, ECB was not detected in any planting date or hybrid for most of the past 4 years. The last planting date of the non-Bt hybrid Providence had a peak CEW density of 0.65 larvae per ear. These results provide ongoing value to sweet corn growers, confirming a low risk of O. nubilalis at this location in MN, and by contrast, the planting dates that continue to be at high-risk to H. zea.A significant outcome of the research, is that we confirmed a high level of CEW resistance to the Cry1Ab, Bt protein (2016- 2018), under field conditions. For example, for 2016-2017, we observed 100% control of CEW larvae in Vip3a sweet corn ears (known high-dose, combined ith Cry1Ab). However, with the Cry1Ab event alone, we found 0.0% control, and actually higher numbers of larvae per ear (2.3 in 2016; 0.89 in 2017) compared to the untreated non-Bt ears (1.60 in 2016; 0.78 in 2017). These results provide evidence of resistant phenotypes via low/zero efficacy by Cry1Ab, but also illustrate the value of using Bt and non-Bt sweet corn as an "In-field screen" for early detection of resistance. Sweet corn as a trap crop with push-pull strategy: a) Through planting date and variety manipulation create attractive plantings of sweet corn around a larger sweet corn field for H zea: We identified at-risk planting and harvest dates for CEW, which are later than June 10th and August 31st, respectively. We evaluated several attractants and identified a potential mixture of molasses and Rimon (an insect growth regulator) that holds promise for use in a push pull system. However, after 3 years of research, we found that the treatments did not provide consistent results. b) In addition to creating attractive trap crop, use of Magnet attractant and insecticide to manage adult population of H. zea moths; After 3 years of research, we have determined that the use of an attractant like Magnet will only provide a significant added level of control when pyrethroid resistance is present in the current years' H. zea population, which is variable year to year as moths migrate into MN each season. Therefore, we began to asses the use of molasses (less expensive alternative to Magnet) in combination with Rimon, an insect growth regulator, that should effect moths fecundity regardless of the insecticide resistance status of exposed moths. Data from 2017 suggests that H. zea populations were susceptible to pyrethroids (higher level of susceptibility vs2015-2016). Treated small plots had a per ear density of 0.05 and treated large plots had a density of 0.01 per ear. Untreated check plots were at 0.26 H. zea per ear. However, given our results, and the cost of treatment, we do not believe this strategy will be cost-effective; this project was terminated in 2018. Impact of Orius spp. on populations of H. zea in sweet corn: a) Quantify H. zea egg consumption - cage studies & molecular confirmation: Methods were developed for obtaining reliable estimates of Orius spp. predation on CEW eggs under field conditions were developed, focusing on the tassel to silking stages of sweet corn. Orius adults and nymphs have been consistently abundant (0.5 to >3 per ear), when focusing on ears that are 7-21 days in age. Results from the molecular study was completed and published his year (Peterson et al. 2018). b) Develop a sequential sampling plan for Oriusadults; Additional data sets for Orius spp. were collected from sweet corn plots at the Rosemount ROC in 2018 over a range of planting dates and growth stages. Data sets for sample plan development were collected using a sample unit of the primary ear on a single sweet corn plant and a sample size of 30 ears. Data conitinue to be analyzed. The analysis will be completed using Resampling for Validation of Sampling Programs (RVSP) software, developed by WD Hutchison and SE Naranjo. Potential, high-risk, invasive species: Helicoverpa armigera: a) Multistate monitoring in the Midwest using pheromone traps.This project was terminated in 2018, due to a lack of H. armigera moth detections in MN during the previous 3 years of monitoring. This effort included additoinal monitoring by staff with the MDA, and via collaborations with the Wisconsin Dept. of Agric. as well. In brief, since the beginning of the project, the current pheromone lures commercially available for H. armigera have not improved. This resulted in excess H. zea moths captured in traps baited with the H. armigera lure, and in many cases hundreds of H. zea moths captured. High captures of H. zea is very in-efficient in that all moths must still be dissected, and male genetalia carefully examined, to distinguish the two species. Also, next gen. sequencing tools are still not ready for field use; this should eventually allow for rapid identification of the two species, and the zea x armigera hybrid that can also occur. Given these obstacles, the project was terminated after the 2017 season.

Publications

• Type: Other Status: Published Year Published: 2018 Citation: Burkness, E.C., S.J. Wold, and W.D. Hutchison 2018. Insecticidal control of lepidopteran pests in sweet corn, 2017. Arthropod Management Tests. 43: DOI: 10.1093/amt/tsy005
• Type: Other Status: Awaiting Publication Year Published: 2019 Citation: Burkness, E.C., S.J. Wold, and W.D. Hutchison 2019. Insecticidal control of lepidopteran pests in sweet corn, 2018. Arthropod Management Tests. 44: (in press)
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Peterson, J. A., E. C. Burkness, J. D. Harwood, and W. D. Hutchison. 2018. Molecular gut-content analysis reveals a strong trophic connection between the insidious flower bug Orius insidiosus and corn earworm Helicoverpa zea in sweet corn. Biological Control. 121:1-7, DOI: 10.1016/j.biocontrol.2018.02.006
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Dively, G.P., P.D. Venugopal, D. Bean, J. Whalen, K. Holmstrom, T.P. Kuhar, H.B. Doughty, T. Patton, W. Cissel, & W.D. Hutchison. 2018. Regional pest suppression associated with widespread Bt maize adoption benefits vegetable growers. Proc. National Acad. Sciences (PNAS). 115(13): 3320-3325. https://doi.org/10.1073/pnas.1720692115
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Deans, C.A., Sword, G.A., Lenhart, P. A., Burkness, E., Hutchison, W.D., Behmer, S.T. 2018. Quantifying Plant Soluble Protein and Digestible Carbohydrate Content, Using Corn (Zea mays) As an Exemplar. J. Vis. Exp. (138), e58164, doi:10.3791/58164

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Fresh-market sweet corn/snap bean growers, and members of the Midwest Food Processors Assoc. (3-state region of MN, WI, IL), as well as Crop Consultants and MN Extension IPM representatives. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?During 2017, we continued to provide research and Pest-alert notifications for H. zea and O. nubilalis to the VegEdge web site (www.vegedge.umn.edu). This included weekly moth flight upates, summarizing out data with that of several collaborators; e.g., for H. zea, this is found at:https://www.vegedge.umn.edu/moth-data/cew-info This site is also a companion site to the MN Extension IPM Program page, at: (www.mnipm.umn.edu), where pest alerts and other emerging issues, such as invasive species activity, is reported. In addition, research updates were delivered at a summer Field Day, hosted by the UMORE Park, Rosemount Expt. Stn. in July, 2017, and results were also reviewed during an invited presentation at the Annual Meeting of the Midwest Food Processors Assoc., Rochester, MN (Nov. 2017). What do you plan to do during the next reporting period to accomplish the goals?In 2018, in preparation for the final report, we will be completing all objectives, including a complete multi-year analysis fo the sentinel plot data for H. zea and O. nubilalis.

Impacts
What was accomplished under these goals? 1) Sentinel plots for resistance monitoring of H. zea and O. nubilalis a) Annual insecticide efficacy trial - small plot: To evaluate the efficacy of insecticides for the European corn borer (Ostrinia nubilalis) and the resistance status of corn earworm (Helicoverpa zea), a comprehensive insecticide trial was conducted, which included experimental adjuvants, at the Rosemount Exp. Stn., Rosemount, MN.In2017, several insecticide treatments provided >90% control of H. zea in sweet corn (Table 1) confirming acceptable levels of control. Background populations of H. zea was moderate at 0.49 larvae per ear. Surprisingly, O. nubilalis were not detected in any treatments of the trial. However, this outcome (as in 2016) also suggests that the areawide suppression effect due to Bt field corn use, is continuing in this area of state, which is a similar trend for most of the state; b) Field corn planted every 2 weeks starting at May 1st until June 30th with non-Bt hybrid and hybrids containing Smartstax and Viptera events. Both Bt and non-Bt field corn and sweet corn hybrids were planted in 2017 covering a range of transgenic events (Cry1Ab, Vip3a, and Cry1F) for control of Lepidopteran pests in corn. Five planting dates were established and only the field and sweet corn hybrid expressing Vip3a provided complete control of H. zea across all planting dates.Again, O. nubilalis was not detected in any planting date or hybrid. The last planting date of the non-Bt hybrid Providence had a peak H. zea density of 0.65 larvae per ear. These results provide ongoing value to sweet corn growers, confirming a low risk of O.nubilalis at this location in MN, and by contrast, the planting dates that continue to be at high-risk to H. zea. 2) Sweet corn as a trap crop with push-pull strategy: a) Through planting date and variety manipulation create attractive plantings of sweet corn around a larger sweet corn field for Helicoverpa zea: We have identified at-risk planting and harvest dates for H. zea, which are later than June 10th and August 31st, respectively. We are currently experimenting with attractants and have identified a potential mixture of molasses and Rimon (an insect growth regulator) that holds promise for use in the push pull system. Work continues on determining how to combine hybrid maturities with attractants to develop a planting strategy for use in managing H. zea; b) In addition to creating attractive trap crop, use of Magnet attractant and insecticide to manage adult population of H. zea moths; After 3 years of research, we have determined that the use of an attractant like Magnet will only provide a significant added level of control when pyrethroid resistance is present in the current years' H. zea population, which is variable year to year as moths migrate into MN each season. Therefore, we have started looking into the use of molasses (a cheaper alternative to Magnet) in combination with Rimon, an insect growth regulator, that should effect moths fecundity regardless of the insecticide resistance status of exposed moths. Data from 2017 suggests that H. zea populations were susceptible to pyrethroids (higher level of susceptibility vs 2015-2016). Treated small plots had a per ear density of 0.05 and treated large plots had a density of 0.01 per ear. Untreated check plots were at 0.26 H. zea per ear. Given our results to date, and the cost of treatment, we do not believe this strategy will be cost-effective for growers. 3) Impact of Orius spp. on populations of H. zea in sweet corn a) Quantify H. zea egg consumption - cage studies & molecular confirmation; method development for obtaining reliable estimates of Orius spp. predation on H. zea eggs under field conditions have been developed, focusing on the tassel to silking stages of sweet corn. Orius adults and nymphs have been consistently abundant (0.5 to >3 per ear), when focusing on ears that are 7-21 days in age. Results from the molecular study was completed and accepted for publication this year (Peterson et al.).b) Develop a sequential sampling plan for Orius adults; Nine additional data sets for Orius spp. were collected from sweet corn plots at the Rosemount ROC in 2017 over a range of planting dates and growth stages. Data sets for sample plan development were collected using a sample unit of the primary ear on a single sweet corn plant and a sample size of 30 ears. Data will be entered and analyzed using Resampling for Validation of Sampling Programs (RVSP) software, developed by Drs. W.D. Hutchison and S.E. Naranjo. 4) Potential, high-risk, invasive species: Helicoverpa armigera a) Multistate monitoring in the Midwest and South using pheromone traps; b) Testing H. armigera pheromone lure(s) for host specificity; c) Determine consistent and reliable method for adult identification of H. armigera vs. H. zea. Because H. zea and H. armigera are now known to hybridize, in 2017, a pheromone trap was setup in Minnesota at the Rosemount ROC using a standard H. zea lure from Hercon Environmental to assess moth populations for species composition. Unfortunately, the current pheromone lure that is commercially available for H. armigera continues to catch numerous H. zea moths, and cannot be used as a reliable trapping system. All moths that were captured in the trap were collected and will be shipped to collaborator,Dr. Greg Sword at Texas A&M for identification via molecular markers.

Publications

• Type: Book Chapters Status: Published Year Published: 2017 Citation: Hutchison, W. D. and T. M. Cira. 2017. Economically important maize insect pests, pp. 263-292. In: Watson, D. (ed.), Achieving sustainable cultivation of maize, Vol. 2: Cultivation techniques, pest and disease control. Burleigh Dodds Science Publishing, Cambridge, UK.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Svobodova, Z., E. C. Burkness, O. Skokova Habustova, and W. D. Hutchison. 2017. Predator preference for Bt-fed Spodoptera frugiperda (Lepidoptera: Noctuidae) prey: Implications for insect resistance management in Bt maize seed blends. J. Economic Entomology 110: 13171325.
• Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Peterson, J. A., E. C. Burkness, J. D. Harwood, and W. D. Hutchison. 2017. Molecular gut-content analysis reveals a strong trophic connection between the insidious flower bug Orius insidiosus and corn earworm Helicoverpa zea in sweet corn. Biological Control (submitted).
• Type: Journal Articles Status: Submitted Year Published: 2017 Citation: Burkness, E. C., S. J. Wold-Burkness, and W. D. Hutchison 2017. Insecticidal control of Lepidopteran pests in Minnesota sweet corn, 2017. Arthropod Management Tests (submitted).

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Fresh-market sweet corn/snap bean growers, and Midwest Food Processors (3-state region of MN, WI, IL), as well as Crop Consultants and MN Extension IPM representatives. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?During 2016, the VegEdge web site (www.vegedge.umn.edu) was significantly upgraded to provide weekly graphical updates of the 2016 Corn Earworm and European corn borer flights. This site was also connected to a new MN Extension IPM site (www.mnipm.umn.edu), where more frequent pest alerts were posted. What do you plan to do during the next reporting period to accomplish the goals?In 2017, we will continue all planned objectives, and move toward completion of selected objectives such as the Orius sampling plan, and complete a multi-year analysis of the senntinel plot data for both H. zea and O. nubilalis.

Impacts
What was accomplished under these goals? 1) Sentinel plots for resistance monitoring ofH. zea(corn earworm) and O. nubilalis (European corn borer):a) Annual insecticide efficacy trial - small plot. The 2016insecticide trial was conducted to evaluate efficacy of new and existing insecticide active ingredients against H. zea and O. nubilalis.Several insecticide products provided >90% control of both target pests in sweet corn,confirming acceptable levels of control. Given the recent problems with pyrethroid resistance, the performance of Coragen was a positive outcome. The 2016 H. zea moth flight was one of the highest in the past 5 years; the background population density in untreated, non-Bt ears was also high at at 1.51 larvae per ear. b) Field corn planted every 2 weeks starting at May 1stthrough June 30th with non-Bt hybrids and hybrids containing Smartstax and Viptera events; both field corn and sweet corn hybrids were planted in 2016 covering a range of transgenic events (Cry1Ab, Vip3a, and Cry1F) for control of Lepidopteran pests in corn, as well as non-Bt hybrids.Five planting dates were established and only the sweet corn hybrid expressing Vip3a provided complete control of H. zea. All transgenic hybrids provided 100% control of O. nubilalis, which again occured at very low levels.The latest planting date of non-Bt hybrids had a peak ear infestation of 100% with a density of 2.12 H. zea larvae per ear, with 10.2 kernels damaged per ear, demonstrating the potential of H. zea as a pest of corn. 2) Sweet corn as a trap crop with push-pull strategy a) Through planting date and variety manipulation create attractive planting of sweet corn around larger sweet corn field for Helicoverpa zea; Despite identifying at risk plantings and harvest dates after June 10th and August 31st, respectively, we are still determining how to combine hybrid maturities with attractants to develop a planting strategy for use in managing H. zea; b) In addition to creatingattractive trap crops, use of Magnet attractant and insecticides to manage adult populations of H. zea moths; the Magnet attractant did not provide a decrease in H. zea populations when compared to untreated sweet corn plots located 1200 ft away where no Magnet was used.The Magnet treatment led to populations of 0.23 H. zea per ear and the untreated plots located 1200 ft away from the Magnet plots had populations of 0.09 H. zea per ear. Potential issues with corn lodging due to high winds associated with thunderstorms may have contributed to inconsistent results;3)Impact of Orius spp. on populations of H. zea in sweet corn a) Quantify H. zea egg consumption - cage studies & molecular confirmation; methods for obtaining reliable estimates of Orius spp. predation on H. zea eggs under field conditions continues; b) Develop a sequential sampling plan for Orius adults; twelve additional data sets for Orius spp. were collected from sweet corn plots at the Rosemount Experiment Station in 2016 over a range of planting dates and growth stages. Data sets were collected using a sample universe of the primary ear on a single sweet corn plant with in a sweet corn field and a sample size of 30. Data will be entered and analyzed using Resampling for Validation of Sampling Programs (RVSP) software; 4) Potential, high-risk, invasive species: Helicoverpa armigera a) Multistate monitoring in the Midwest and South using pheromone traps; b) Testing H. armigera pheromone lure(s) for host specificity; c) Determine consistent and reliable method for adult identification of H. armigera vs. H. zea. A pheromone trap was setup in Minnesota at the Rosemount Research and Outreach Center using H. armigera lures from USDA APHIS. All moths that were captured in the trap were collected and shipped to Dr. Greg Sword at Texas A&M for identification via molecular analysis.

Publications

• Type: Other Status: Awaiting Publication Year Published: 2016 Citation: Burkness, EC, Wold-Burkness, SJ, Hutchison, WD. 2016. Insecticidal control of corn earworm and European corn borer in Minnesota sweet corn, 2016. Arthropod Management Tests. vol. 41 (in press)
• Type: Journal Articles Status: Submitted Year Published: 2017 Citation: Svobodova, Z, EC Burkness, O Skokova Habustova, and WD Hutchison. 2017. Predator preference for Bt-fed prey:Implications for insect resistance management in Bt maize seed blends. Journal of Economic Entomology (submitted).

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Entomologists, Biotechnology scientists, Growers, Cooperative Extension staff, Crop Consultants. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Insect migration symposium co-organized at the annual national Entomological Society of Amercia meeting in Minneapolis, MN (2015). How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Devleopment and implementation of research methods will continue as well as analyses of data already collected. Collaborations will continue within the U.S. and Brazil to document the risk of H. armigera invasion in the U.S.

Impacts
What was accomplished under these goals? The following accomplishments are summarized for each of 4 objectives: 1) Sentinel plots for resistance monitoring of H. zea and O. nubilalis a) Annual insecticide efficacy trial on sweet corn - small plot; efficacy was evaluated for new and existing insecticide active ingredients against H. zea and O. nubilalis. Several insecticide products provided 100% control of both target pests in sweet corn confirming acceptable levels of control. However, populations of both pest species were very low so limited information can be drawn from trial results. b) Field corn planted every 2 weeks starting at May 1st until June 30th with non-Bt hybrid and hybrids containing Smartstax and Viptera events; along with planning to establish which transgenic hybrids and events are most appropriate for inclusion in the trial, we have also identified a shift in the peak flight of H. zea at the Rosmeount Research and Outreach Center over the last 5 years. Peak flight has moved to an average date of Sept. 2 vs previous estimates of Aug. 20. This information will help guide planting dates for subsequent trials. 2) Sweet corn as a trap crop with push-pull strategy a) Through planting date and variety manipulation create attractive planting of sweet corn around larger sweet corn field for Helicoverpa zea; through the use of sweet corn planting date studies we have been able to identify planting/harvest dates that are most at risk for infestations of H. zea and O. nubilalis, which on average are after June 10 and August 31 for planting and harvest dates, respectively. This information will guide the design of the subsequent trials; b) In addition to creating attractive trap crop, use of Magnet attractant and insecticide to manage adult population of H. zea moths; despite the promising preliminary data that were collected in 2014, evaluations of the attractant Magnet combined with insecticide vs. untreated sweet corn were inconclusive in 2015 due to very low H. zea populations at the Rosemount Research and Outreach Center. Preparations are underway to evaluate Magnet in 2016. 3) Impact of Orius spp. on populations of H. zea in sweet corn a) Quantify H. zea egg consumption - cage studies & molecular confirmation; methods are being developed to evaluate consumption of H. zea eggs by Orius spp. under field conditions. Constraints on how long H. zea dna remains viable in Orius spp. after feeding on H. zea eggs are being evaluated to ensure reliable test results; b) Develop a sequential sampling plan for Orius adults; data analysis is ongoing using data sets for Orius spp. that were collected from sweet corn and resampling software using boot strap simulations to validate sampling plans using independent sampling data. 4) Potential, high-risk, invasive species: Helicoverpa armigera a) Multistate monitoring in the Midwest and South using pheromone traps; b) Testing H. armigera pheromone lure(s) for host specificity; c) Determine consistent and reliable method for adult identification of H. armigera vs. H. zea. Pheromone traps were setup in Minnesota at the Rosemount Research and Outreach Center using H. armigera lures obtained from USDA APHIS. Traps were also setup in Texas. All moths captured in the pheromone traps were shipped to Dr. Sword at Texas A&M for identification and to verify the efficacy of currently available pheromone lures. In addition, these samples will also be used to establish reliable identification methods for H. armigera moths. Larvae were also collected from corn fields in White Bear Lake, MN and Lamberton, MN and shipped to Dr. Sword at Texas A&M for use in molecular analyses to determine if there are any H. armigera X H. zea hybrids present in Minnesota corn fields.

Publications

• Type: Journal Articles Status: Published Year Published: 2015 Citation: Burkness, E. C., T. M. Cira, S. E. Moser, and W. D. Hutchison. 2015. Bt maize seed mixtures for Helicoverpa zea: Larval movement, development and survival on non-transgenic maize. Journal of Economic Entomology 2015; doi: 10.1093/jee/tov253.

Progress 07/01/14 to 09/30/14

Outputs
Target Audience: Entomologists, Biotechnology scientists, Growers, Cooperative Extension staff, Crop Consultants. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Regarding Obj. 4, and H. armigera, I co-organized a symposium at the national Entomol. Soc. of America meetings, Portland, OR (2014), to review the current knowledge available to assess the risk of this pest invading N. America, and the potential impacts on U.S. agriculture. Attendance duirng the 5-hour session averaged 80-100. Attendees included officials from USDA APHIS. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Collaborations will continue within the U.S. (e.g., in TX) and with colleagues in Brazil to further quantify, and complete the first publication on the risk of H. armigera to the U.S.

Impacts
What was accomplished under these goals? As this new project was just initiated in July, 2014, we do not have extensive field data available. However, the following accomplishments are summarized for each of 4 objectives: 1) Sentinel plots for resistance monitoring of H. zea and O. nubilalis a) Annual insecticide efficacy trial - small plot; an insecticide trial was conducted to evaluate efficacy of new and existing insecticide active ingredients against H. zea and O. nubilalis. Several insecticide products provided >90% control of both target pests in sweet corn (see Table 1) confirming acceptable levels of control. b) Field corn planted every 2 weeks starting at May 1st until June 30th with non-Bt hybrid and hybrids containing Smartstax and Viptera events; planning is currently ongoing to establish which transgenic hybrids and events are most appropriate for inclusion in the trial. 2) Sweet corn as a trap crop with push-pull strategy a) Through planting date and variety manipulation create attractive planting of sweet corn around larger sweet corn field for Helicoverpa zea; planning continues to identify the best planting dates and hybrids to use for this objective; b) In addition to creating attractive trap crop, use of Magnet attractant and insecticide to manage adult population of H. zea moths; preliminary data were collected in 2014 to demonstrate the efficacy of the attractant Magnet combined with insecticide vs. an untreated plot of sweet corn. Both the total number of H. zea larvae and feeding damage were found to be significantly lower in the untreated plot with Magnet and insecticide applied around the perimeter vs. the untreated plot located 1200ft away without Magnet and insecticide applied around the perimeter. The density of H. zea larvae per sweet corn ear was 0.19 in the untreated plot with Magnet and 0.66 in the untreated plot without Magnet (df = 6; t value = -3.14; P = 0.0199). 3) Impact of Orius spp. on populations of H. zea in sweet corn a) Quantify H. zea egg consumption - cage studies & molecular confirmation; planning is underway to develop experimental methods to evaluate consumption of H. zea eggs by Orius spp. under field conditions; b) Develop a sequential sampling plan for Orius adults; data sets for Orius spp. were collected from sweet corn plots at the Rosemount Experiment Station in 2014. Data sets were collected using a sample universe of the primary ear on a single sweet corn plant with in a sweet corn field. The sample size was 40 primary ears and data were recorded from 2 planting dates of sweet corn throughout the month of August when peak H. zea activity typically occurs in Minnesota. 4) Potential, high-risk, invasive species: Helicoverpa armigera a) Multistate monitoring in the Midwest and South using pheromone traps; b) Testing H. armigera pheromone lure(s) for host specificity; c) Determine consistent and reliable method for adult identification of H. armigera vs. H. zea. Planning is underway with colleagues in Brazil and the Southern U.S. to allow coordination of trap cooperators and supplies and to provide a supply of moth specimens for use in determining moth identification methods.

Publications

• Type: Journal Articles Status: Published Year Published: 2014 Citation: White, J. A., E. C. Burkness, and W. D. Hutchison. 2014. Biased sex ratios, mating frequency and Nosema prevalence in European corn borer, at low population densities. Journal of Applied Entomology 138: 195-201.