COMPARISON OF AERIAL AND CHEMIGATION APPLICATION FOR WESTERN BEAN CUTWORM MANAGEMENT IN INTENSIVE CORN PRODUCTION

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: ACTIVE
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1030254
• Grant No.: 2023-68008-39856
• Cumulative Award Amt.: $300,000.00
• Proposal No.: 2022-10050
• Project Start Date: May 15, 2023
• Project End Date: May 14, 2026
• Grant Year: 2023
• Program Code: [A1701]- Critical Agricultural Research and Extension: CARE

Recipient Organization
UNIVERSITY OF NEBRASKA
(N/A)
LINCOLN,NE 68583

Performing Department
(N/A)

Non Technical Summary
The western bean cutworm (WBC; Striacosta albicosta) is an insect pest that can cause severe damage on corn ears by larval feeding. Only the Vip3A Bt protein can provide adequate protection from WBC but it is not available in all corn hybrids. In intensive corn production, most growers apply insecticides by airplane, but spray coverage is not uniform. Some growers apply insecticides through the irrigation system (chemigation). Inadequate insecticide application may lead to failures of WBC control in corn. Exposing this pest to sublethal dosages may lead to the development of insecticide resistance. Thus, good coverage of treated plants should be the goal of pesticide applications.Objectives: 1) Compare the efficacy and efficiency of aerial and chemigation applications in the field as a part of on-farm research to optimize pest control and spray characteristics (e.g., coverage, canopy penetration, and carrier volume); 2) Simulate aerial and chemigation applications in controlled conditions with field-collected populations to confirm the effect of certain application methods and insecticides on spray efficiency and pest control efficacy; 3) Communicate knowledge gained by providing results and recommendations to farmers, crop consultants, and professional applicators to impact pest management decision-making.Impact: Increased knowledge of application methods lead to greater insecticide efficacy and efficiency, which can provide better resistance management and ensure farmers with more tools for WBC control in the future. This project will address critical challenges using an integrated research and extension project addressing USDA's CARE Program Area Priority by developing, improving, and targeting crucial producers' problems focused on crop production, pesticide application and protection, plant health, and food quality.

Animal Health Component

100%

Research Effort Categories

Basic

0%

Applied

100%

Developmental

0%

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

western bean cutworm

aerial application

chemigation

insecticide

integrated pest management

Goals / Objectives
Compare the efficacy and efficiency of aerial and chemigation applications in the field as a part of on-farm research to optimize pest control and spray characteristics (e.g., coverage, canopy penetration, and carrier volume).Simulate aerial and chemigation applications in controlled conditions with field-collected populations to confirm the effect of certain application methods and insecticides on spray efficiency and pest control efficacy.Communicate knowledge gained by providing results and recommendations to farmers, crop consultants, and professional applicators to impact pest management decision-making.

Project Methods
Objective One: Compare the efficacy and efficiency of aerial and chemigation applications in the field as a part of on-farm research to optimize pest control and spray characteristics (e.g., coverage, canopy penetration, and carrier volume).Field trials will be conducted at 4-6 locations selected based on history of pest pressure, presence of appropriate irrigation system, and cooperation with landowners.Results from the Nebraska Corn Board survey will help us to determine which factors will be tested, including: application timing (in relation to crop/pest phenology), product choice and rates, sprinkler/nozzle types, carrier volume, etc.We will choose a maximum of 10 treatments, replicated a minimum of four times. Plot size and experimental design will be based on the size of the farmers' fields, capabilities of their irrigation system, and in consultation with the aerial applicators.Western bean cutworm populations will be monitored using pheromone traps located at the edges of the field. Traps will be checked every 3-4 days, and pheromone and insecticide strips replaced every two weeks until the moth flight is complete.Once moths have been caught in the traps, the field will be scouted once every three days. A minimum of 20 plants at 5 randomly selected locations (total 100 plants) within the trial will be non-destructively examined on each scouting date.The aerial application will be performed with an airplane that is typically used for pesticide applications. Critical responses that will be collected during the insecticide application include coverage (deposition efficacy), canopy penetration, and droplet size.For aerial application, these factors will be measured using water sensitive paper (WSP). Prior to aerial application, WSP will be placed horizontally in the field and positioned within the corn canopy at three locations representing the Top (tassel height), Middle (ear height) and Bottom (midway between the ear and the ground) of the canopy. After each aerial spray pass, WSPs will be collected and stored in dry conditions. WSPs will be scanned and processed to determine deposition rate (L/ha) and droplet size diameters for Top, Middle and Bottom canopy locations. The basis for this methodology was described by Souza et al. (2019).Chemigation applications will be performed with central pivot or lateral move irrigation systems. A pump will be used to apply the insecticide through the irrigation system onto the field.For chemigation applications, application characteristics will be measured with PVC pipe jar holders set up in designated rows. Each holder will consist of three jars that will be set up at the same heights as for aerial application (Top, Middle and Bottom of corn canopy).Contents of the jars will be analyzed by LCMS at a commercial lab to determine the concentration of insecticide active ingredient present in the sample.Each plot will be monitored for the presence of WBC by destructive sampling of 10 plants/plot at the following time points: pre-application and 3, 7, 14, and 21 days after application. At 28 days after application, 10 ears per plot will be collected and assessed for the presence and size of larvae in the ears, and the amount of feeding damage will be measured. Impact on crop yield will be assessed by hand-harvesting 10 ears per plot when grain is at mature harvest time.An important measure will also be the residual activity of selected insecticides: corn tissue samples will be collected following chemical application to determine how long insecticides remain active against WBC. Four corn leaves from Middle of corn canopy will be collected from each plot 1 and 5 days after treatment. Corn leaf discs cut from the field-collected leaves will be placed on the bottom of each Petri dish. Each Petri dish will be infested with 10 1st instar WBC and assessed for mortality 16, 24, and 48 hours later.Objective Two: Simulate aerial and chemigation applications in controlled conditions with field-collected populations to confirm the effect of certain application methods and insecticides on spray efficiency and pest control efficacy.To conduct laboratory research, WBC adults and egg masses will be collected from the field and reared in the lab using methods described previously (Montezano et al. 2019a;Montezano et al. 2019b; Coates et al. 2020).A multi-nozzle research track spray chamber will be used to simulate aerial applications of commercial insecticides. The spray characteristics measured in Objective 1 will be reproduced by selecting nozzles and operating pressures in the spray chamber to best mimic the aerial applications from the field. This will follow previously developed methods (Souza et al. 2019, Montezano et al. 2019a).Corn leaf discs will be placed on the bottom of each Petri dish. Four Petri dishes will be sprayed for each treatment and replicated 4 times. Dishes sprayed with water only will be used as controls. Petri dishes will be open for 30 min after treatment to completely dry before WBC infestation.To simulate chemigation in controlled conditions, corn leaves will be placed inside of chamber to receive insecticide. After application, when corn leaves are completely dry, they will be cut into discs and placed in Petri dishes before WBC infestation. Four Petri dishes will be used per treatment.We will test three larval stadia: 20 neonates (<36 h old), 10 second instar, and 10 third-instar larvae from field-collected populations per Petri dish. Larvae will be transferred to each Petri dish using a paintbrush. Mortality will be recorded at 16h, 24h and 48h after infestation. Larvae that are not moving on gentle touch with paint brush will be considered dead.Objective Three: Communicate knowledge gained by providing results and recommendations to farmers, crop consultants, and professional applicators to impact pest management decision-making.The PD's, consultants, and graduate student will share the essential findings of this project with stakeholders through Nebraska Extension events such as Crop Production Clinics, Pesticide Resistance Management Workshops, Water and Crops field day, commodity board meetings, Nebraska Independent Crop Consultants annual conference, Nebraska Aviation Trades Association annual meeting, and many more.The results of the study will be available in publications like CropWatch and NebGuides, and also through social media and the FarmBits Podcast.Project results will also be presented at regional and national scientific meetings.We will share the knowledge gained from the chemigation part of the study by creating a publication for Nebraska Extension's NebGuide series. In collaboration with the Nebraska Pesticide Safety Education Program (PSEP), the content of this NebGuide will become part of the chemigation certification training that all Nebraskans must complete to be licensed to conduct chemigation on their farms.The impact of this objective will be measured through pre/post surveys as well as follow-up surveys. Surveys would be distributed to stakeholders during Nebraska Extension events where the results of this research are being shared. We will pay particular focus on the participants in the chemigation certification trainings conducted by PSEP.

Progress 05/15/23 to 05/14/24

Outputs
Target Audience:The knowledge gained from this project will be applicable to Nebraska but also to the broader Great Plains and Great Lakes regions, where western bean cutworm (WBC) is a serious problem in both corn and dry bean crops. Application efficiency data will also be applicable to management for other key pests targeted by pesticide applications at similar crop phenology, such as corn rootworm beetles, corn earworm, fall armyworm, and spider mites. Results will be shared with scientific audiences at conferences such as the Entomological Society of America, but also on Nebraska Extension events, the Nebraska Corn Board and Dry Bean Commission commodity board meetings, Nebraska Independent Crop Consultants annual conference, and Nebraska Aviation Trades Association annual meeting. Changes/Problems:In 2023, WBC in the fields of interest for this project achieved the economic threshold, meaning that 5-8% of the corn plants had egg masses or larvae. However, infestation was not uniform across all plots, which influenced the inability to detect statistical differences between treatments. In 2024, an artificial infestation of corn plants with WBC egg masses will be performed to achieve evenly distribution on research plots on-farm. What opportunities for training and professional development has the project provided?At Nebraska, personnel closely involved in this project included international internship student (Barbara Rodrigues Silveira from Brazil in 2023) and a PhD student (MS Andrea Rilakovi?). The doctoral student also developed her mentorship skills by joining the PI in advising the undergraduate student. Students have received extensive training in one or more of the following areas: western bean cutworm biology, optimization of WBC rearing procedures, conducting field experiments, insecticide application techniques, and oral and poster presentation skills. All students and other scientific personnel will be able to present their research findings at the Entomological Society of America or other conferences. How have the results been disseminated to communities of interest?In 2023 and 2024, a poster and presentations were presented at the Entomological Society of America conference, exploring the efficiency of applied insecticides and insect exposure to the treated leaves (Objective 1). Additionally, extension presentations in Nebraska were held to the local farmers, stakeholders, and aerial applicators. What do you plan to do during the next reporting period to accomplish the goals?Objective 1. Replicate and complete field applications during summer of 2024 of the insecticides using aerial and chemigation applications on-farm. Replicate exposure of WBC first and third larval instars to the field-treated leaves. Objective 2. Simulate aerial and chemigation application in controlled conditions using the same parameters from the field research (Objective 1). Objective 3. Communicate findings gained on (Objective 1 and 2) to agricultural stakeholders through practical recommendations that will enhance insecticide input efficiency, sustainability, and profitability. The PD's, consultants, and graduate student will share the essential findings of this project with stakeholders through Nebraska Extension events such as Crop Production Clinics, Pesticide Resistance Management Workshops, Water and Crops field day, the Nebraska Corn Board and Dry Bean Commission commodity board meetings, Nebraska Independent Crop Consultants annual conference, Nebraska Aviation Trades Association annual meeting, and many more.

Impacts
What was accomplished under these goals? 1. Compare the efficacy and efficiency of aerial and chemigation applications in the field as a part of on-farm research to optimize pest control and spray characteristics (e.g., coverage, canopy penetration, and carrier volume). Aerial and chemigation applications on-farm The first year of the field experiment was conducted to evaluate the efficacy and efficiency of aerial and chemigation applications in the field as a part of on-farm research to optimize pest control and spray characteristics for WBC management. Five treatments were evaluated: two active ingredients (chlorantraniliprole or bifenthrin) applied by airplane (2GPA) or chemigation (0.2 and 0.5 ac-in), plus an untreated control. Chlorantraniliprole was applied at 1.2 fl/oz per acre, while bifenthrin was applied at 5 fl/oz per acre when the economic threshold was achieved and 95% of the corn field was tasseled. Each plot was monitored for the presence of live and dead WBC adults, eggs, and larvae by the destructive sampling of 10 plants/plot at the following time points: pre-application and 7, 14, and 21 days after application. At 28 days after application, 10 ears per plot were collected and assessed for the presence and size of larvae in the ears, and the amount of feeding damage (cm2) was measured. Results showed that there were no statistical differences between treatments. This study will be repeated in 2024. Insect exposure to field-treated leaves The first year of the laboratory experiment was conducted to evaluate survival rates for the first and third instars of WBC exposed to corn leaves treated in the field using aerial and chemigation applications. Five treatments were evaluated: two active ingredients (chlorantraniliprole or bifenthrin) applied by airplane (2GPA) or chemigation (0.2 or 0.5 ac-in), plus an untreated control. After insecticide application, two leaves were collected at both ear and tassel height from each plot on the day of application (0 DAT) and five days after treatment (5 DAT). Each Petri dish with tassel leaves was infested with 20 WBC neonates, while ear leaves were infested with 10 larvae of the third instar. Survival of larvae was observed after 16, 24, and 48 hours. Based on data gathered from preliminary experiments results at 0 DAT showed that aerially applied chlorantraniliprole significantly reduced survival compared with the untreated control. Surprisingly, survival of neonates and third instars was not significantly different at 0 DAT. However, neonates did have significantly lower survival compared to third instars at 5 DAT. The lowest survival rate was observed 48h after infestation but was not statistically different from 24h for 5 DAT. This study will be repeated in 2024. 2. Simulate aerial and chemigation applications in controlled conditions with field-collected populations to confirm the effect of certain application methods and insecticides on spray efficiency and pest control efficacy. This objective will be accomplished in 2024. This research question is based on the data collected from aerial and chemigation applications in the field from 2023. Based on the field experiment, the spray characteristics measured in Objective 1 (primarily deposition rate and distribution of droplet size diameters) will be reproduced by selecting nozzles and operating pressures in the spray chambers to mimic the aerial applications from the field. Chemigation applications will be simulated based on the selection of nozzle types, nozzle heights, water volumes, and product rates used for chemigation applications in the field. 3. Communicate knowledge gained by providing results and recommendations to farmers, crop consultants, and professional applicators to impact pest management decision-making. Knowledge gained from the preliminary study was presented at the Entomological Society of America conferences, Crop Production Clinics and Annual Nebraska Aviation Trades Association Convention. Recommendations from preliminary data from the research conducted in the controlled conditions.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Invited Research Presentation: Rilakovi? A., Zaric M., Golus JA., Vieira BC., Fritz B., Kruger GR., Dorr T., Rudnick DR. & Peterson JA. 2024. Western bean cutworm (S. albicosta) pesticide application efficacy and efficiency in corn in Nebraska. Entomology Society of America North Central Branch (NCB-ESA), Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Contributed Research Poster: Silveira, BRR., Rilakovi? A., Peterson JA. 2023. Mortality of western bean cutworm after exposure to leaves treated by aerial application and chemigation. Entomology Society of America Annual Meeting (ESA), National Harbor, MD.
• Type: Other Status: Published Year Published: 2024 Citation: Extension Presentations: Rilakovi? A., Silveira, BRR., Santana AS., Zari? M., Golus JA, Dorr T., and Peterson JA. 2024. Pesticide Application Technology and Drones in Agriculture, Extension talk at Crop Production Clinics, WCREEC, North Platte, NE. Rilakovi? A., Silveira, BRR., Santana AS., Zari? M., Golus JA, Dorr T., and Peterson JA. 2024. Research updates for aerial and other application methods targeting corn insect pests. Annual Nebraska Aviation Trades Association (NATA) Convention, Kearney, NE.