INSECTICIDE RESISTANCE MONITORING PROGRAM FOR PESTS OF VIRGINIA ROW CROPS AND DEVELOPING NEW PEST MANAGEMENT RECOMMENDATIONS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1018261
• Project Start Date: Dec 7, 2018
• Project End Date: Sep 30, 2023
• Program Code: [(N/A)]- (N/A)

Recipient Organization
VIRGINIA POLYTECHNIC INSTITUTE
(N/A)
BLACKSBURG,VA 24061

Performing Department
Tidewater Agri Research & Extension Ctr

Non Technical Summary
Problem statement. Row crop production (e.g., maize, soybean, cotton, peanut, and small grains) is the dominant use of arable land in Virginia and was valued at $478.4 million in 2016 (USDA/NASS, 2017). Estimates indicate that insect pests have the potential to cause losses between 10% (soybean) and 37% (cotton) of what farmers grow (Oerke, 2006). Declining commodity prices and increasing production costs have resulted in narrow profit margins (estimated at $100-200 per acre) for farmers (Henderson et al., 2012). Producers are looking for affordable ways to manage insect pests. One way to reduce insect management costs is to identify insecticide resistance pests and determine what products offer best control.Relevance to advancing Virginia/Region and USA. Corn earworm Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), is a major pest of corn, cotton, soybean, sorghum, and other agricultural products in Virginia. Corn earworm, along with closely related Heliothine species, are recognized in the US and internationally as one of the top three most devastating pests of agriculture (Reed and Pawar, 1982). In soybean alone, corn earworm control with insecticides costs Virginia growers $1.5 to 2 million dollars annually (Herbert et al., 2014). Control of corn earworm in Virginia and across the Southeast has relied heavily upon the pyrethroid class of insecticides (Jacobson et al., 2009). Pyrethroids offer broad spectrum of activity, relative safety for applicators, and low cost ($2-6 per acre). Insecticidal alternatives for corn earworm control are considerably more expensive ($20-30 per acre). Corn earworm has been trending toward pyrethroid resistance in many regions including the Midwest, Southeast, and Mid-south (Stadelbacher et al., 1990; Hsu and Yu, 1991; Abd-Elghafar et al., 1993; Kanga et al., 1996; Brown et al., 1998; Ottea and Holloway, 1998; Jacobson et al., 2009). Pyrethroids have provided consistent control of corn earworm in Virginia until very recently (unpublished manuscript from "Southern pest management seminar" 1977-present), with more and more Virginia growers reporting pyrethroid spray failures in 2016 and 2017 (S. Taylor, personal communications 2016 and 2017). We propose to use multiple methods including diet overlays, insecticide spray tests, and adult vial assays to evaluate resistance levels in Virginia. The processes we useto monitor and manage pyrethroids resistance in the corn earwormwill serve a model for other insecticide combinations and pests of row crops as they emerge in Virginia.Anticipated Outcomes and Impacts. Results will be used to inform growers of local pest situations, detect regional patterns in insect resistance, and help control pest management costs. This will enable growers to make informed decisions before purchasing and broadcasting

Animal Health Component

100%

Research Effort Categories

Basic

(N/A)

Applied

100%

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

integrated pest management

maize

soybean

corn earworm

pyrethroids

insect resistance management

Goals / Objectives
Results of this projectwill be used to inform growers of local pest situations, detect regional patterns in insect resistance, and help control pest management costs. This will enable growers to make informed decisions before purchasing and broadcasting insecticides, ideally, save time, expense, and decrease environmental residues from repeated pesticide applications.Objectives:1. Use multiple methods (e.g., diet overlays, adult vial tests) to measure insecticide resistance in corn earworm and/or additional crop pests. The processes used to monitor and manage pyrethroids resistance in the corn earworm as described will serve as the template to for other insecticide combinations and pests of row crops as they emerge in Virginia.2. To test multiple insecticides in small plot trials against corn earworm and/or other insect pests. Results will be used to update Virginia Tech Cooperative Extension insecticide spray recommendations for insect pests published annually in "Pest Management Guide: Field Crops".

Project Methods
The processes used to monitor and manage pyrethroids resistance in the corn earworm as described will serve as the template to for other insecticide combinations and pests of row crops as they emerge in Virginia.Objective 1.Diet overlays: Corn earworm larvae will be collected from host plants (e.g., corn, sorghum, peanut, cotton) in multiple locations in Virginia. Collections will be made June - September. Field scouts, cooperative extension agents, and cooperating growers/consultants will be used to identify likely collection locations. Entomology personnel from PI Taylor's laboratory will collect larvae after obtaining permission of the grower to sample and collect in her/his fields. GPS coordinates and the date will be recorded for each collection. Laboratory colonies will be established from these collections by rearing larvae to adulthood, placing male and female adult moths into oviposition containers, and collecting eggs. Neonate larvae that hatch from eggs will be placed on artificial diet and maintained at 27±1°C with a L14:D10 photoperiod until the second larval instar. Larval instar will be estimated by weight and head capsule size. Each colony will consist only of those progeny from a single collection location and date. A minimum of 100 second instar larvae (20-30 mg in size) from the first laboratory generation (F1) will be assessed in diet overlay bioassays (Roush and Miller, 1986; Mascarenhas, 1997). In diet overlay assays, 3 mL of liquid corn-based artificial diet will be pipetted into individual plastic cups and allowed to cool and solidify at room temperature. A 100 ul aliquot of formulated pyrethroid product (e.g., Warrior II, 22.8% ai, Syngenta US, Greensboro, NC, USA) and distilled water solution at different concentrations of active ingredient (as measured by ppm) will be pipetted directly on top of solid diet and shaken to ensure coverage of entire surface. Solution will be given 30 minutes to dry. One larva will be placed directly onto the diet surface in each cup and the cup covered with a ventilated lid. At least 10 larvae (per colony) will be assessed at each concentration; seven to ten concentrations will be tested. Mortality will be assessed at seven days. Mortality will be defined as larvae that do not move or otherwise respond to prodding. Dose-response results will be analyzed against active ingredient concentration with a probit regression analysis. Lethal dose ratios (LD50 and LD95) with 95% confidence intervals will be calculated for each population. Susceptibility to insecticide will be considered significantly different if 95% confidence intervals of lethal dose ratios do not overlap.Adult vial tests: These tests will be used to assess pyrethoid resistance in wild-caught adult male moths. Although the comparison will not be quantitative, populations from different regions of the state (e.g., southeast VA, Eastern Shore, mountains) will be compared to test the relationship, if any, between resistance levels as measured by diet overlays and resistance levels in adult vial assays. Entomology personnel will operate pheromone-baited traps for corn earworm moths at Virginia Agricultural Research and Extension Centers (ARECs) (e.g., Tidewater AREC, Suffolk, and Eastern Shore AREC, Painter) during the growing season (May-September). Three to five traps per location will be positioned in open areas bordering soybean and/or corn fields. Corn earworm moths caught that appear visually healthy (i.e., wings not damaged; majority of wing scales intact) will be assessed for pyrethroid resistance using the adult vial test. The vial test exposes the moths to a residual concentration of pesticide for 24 hours. Vials will be prepared at the Tidewater Agricultural Research and Extension Center following the protocol developed by Fred Musser at Mississippi State University and using technical grade pyrethroid insecticide, with acetone-only vials as the control.Objective 2.Small plot insecticide screening experiments will be established in cotton, peanut, soybean, sorghum, and/or corn at the Tidewater Agricultural Research and Extension Center in Suffolk and/or in fields of cooperating producers. Insecticides will be broadcast at threshold appropriate for each insecticide. Treatments will be chosen from "Pest Management Guide: Field Crops" and consist of low and high rates of recommended products and an untreated control. When possible, insects will be collected for Objective 1 prior to broadcasting insecticides. All other agronomic practices (fertilizer, weed control, fungicide program) will be according to standard Virginia recommendations. Pre- and post-application insect counts will be taken using standard sampling methods (e.g., sweep net, drop cloth). Data to be collected will include insect counts 3 and 7 days after treatment, and crop yield. Data will be analyzed using ANOVA and LSD statistical procedures.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Row crop (e.g., cotton, corn, soybean, peanut, small grains) producers, crop advisors, Cooperative Extension Agents, Ag suppliers, industry reps, scientists, the general public, and university faculty. 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?Pest updates were issued throughout the season via the Virginia Ag Pest and Crop Advisory and weekly zoom sessions. Information was also provided at grower field days, production meetings, and in-field training sessions for agents and crop advisors either virtually or with limited in-person attendance. What do you plan to do during the next reporting period to accomplish the goals?We will continue to conduct research on primary pests of row crops in Virginia.

Impacts
What was accomplished under these goals? 1. Lygus linneolaris populations collected out of weed and crop hosts in Virginia, North Carolina, Georgia, South Carolina, and Alabama were screened for insecticide resistance. Metabolic resistance mechanisms were measured. Assays revealed elevated resistance to acephate and bifenthrin in L. lineolaris populations collected from wild and cultivated hosts in Virginia, North Carolina, and northern Alabama. The highest levels of insecticide resistance were observed with bifenthrin. Mixed-function oxidase (piperonyl butoxide) and esterase inhibitors (S,S,S-Tributyl phosphotrithioate) had a synergistic effect on bifenthrin with resistant populations. Bifenthrin resistant L. lineolaris populations also expressed elevated levels of cytochrome P450 monooxygenase (CYP) and general esterase activity (EST). Synergist and biochemical assay results suggest CYT and EST activity in L. lineolaris intensifies pyrethroid resistance in the Southeast. 2.Replicated small plot experiments were used to test how insecticides performed in the field. Experiments were conducted in cotton (aphids, bollworm, tarnished plant bug, thrips, spider mites), peanut (thrips, southern corn rootworm), wheat (aphids), alfalfa (alfalfa weevil), soybean (stink bug, soybean looper, corn earworm), and corn (western corn rootworm, corn earworm). The resulting recommendations were shared with producers via the Ag Pest and Advisory Blog and Pest Management Guides.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Dorman, S., D. Reisig, S. Malone, and S. Taylor. 2020. Systems approach to evaluate tarnished plant bug (Hemiptera: Miridae) management practices in Virginia and North Carolina cotton. Journal of Economic Entomology. doi: 10.1093/jee/toaa142
• Type: Journal Articles Status: Awaiting Publication Year Published: 2020 Citation: Dorman, S., J. Opoku, H. Mehl, and S. Taylor. 2020. Fusarium hardlock associated with Lygus lineolaris (Hemiptera: Miridae) injury in Southeastern cotton. Plant Disease. doi.org/10.1094/PDIS-03-20-0569-RE
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Kaufman, A., D. Jordan, C. Reberg-Horton, L. Dean, B. Shew, R. Brandenburg, D. Anco, H. Mehl, S. Taylor, M. Balota, L. Goodell, and J. Allen. 2020. Identifying interest, risks, and impressions of organic peanut production: A survey of conventional farmers in the VirginiaCarolina region. Crop, Forage, and Turfgrass Management. doi.org/10.1002/cft2.20042
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Royals, B., R. Brandenburg, A. Hare, D. Jordan, S. Taylor, and S. Malone. 2020. Efficacy of chlorantraniliprole on southern corn rootworm in peanut. Crop, Forage, and Turfgrass Management. doi.org/10.1002/cft2.20045
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Dorman, S., A. Gross, F. Musser, B. Catchot, R. Smith, D. Reisig, F. Reay-Jones, J. Greene, P. Roberts, and S. Taylor. 2020. Resistance monitoring to four insecticides and mechanisms of resistance in Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae) populations of southeastern USA cotton. Pest Management Science. doi.org/10.1002/ps.5940
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Jordan, D., J. Dunne, H. Stalker, B. Shew, R. Brandenburg, D. Anco, H. Mehl, S. Taylor, and M. Balota. 2020. Risk to sustainability of pest management tools in peanut. Agriculture and Environmental Letters. doi.org/10.1002/ael2.20018
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Formella, A., S. Dorman, S. Taylor, and T. Kuhar. 2020. Effects of aggregation lure and tree species on Halyomorpha halys (St�l) (Hemiptera: Pentatomidae) seasonal oviposition. Journal of Economic Entomology. doi.org/10.1093/jee/toz281
• Type: Websites Status: Published Year Published: 2020 Citation: Sprague, C., C. Bradley, and S. Taylor. Pest management to minimize the increase of pesticide resistance: Considerations for weeds, diseases and insects. CropLife International and Take Action. June 2020. https://event.webcasts.com/starthere.jsp?ei=1310604&tp_key=278da76ca6

Progress 12/07/18 to 09/30/19

Outputs
Target Audience:Row crop (e.g., cotton, corn, soybean, peanut, small grains) producers, crop advisors, Extension Agents, Ag suppliers, industry reps, and university faculty. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Field scouts were trained in appropriate protocols for collection, sampling, handling of specimens and reporting. How have the results been disseminated to communities of interest?Pest updates were issued throughout the season via the Virginia Ag Pest and Crop Advisory. Information was also provided at grower field days, production meetings, and in-field training sessions for agents and crop advisors. What do you plan to do during the next reporting period to accomplish the goals?We will continue to pursue research onprimary pests of row cropsin Virginia.

Impacts
What was accomplished under these goals? (1) A total of 685 adult corn earworm moths were collected live from pheromone-baited traps located in Suffolk, VA from June to September 2019 and subjected to the adult vial test using 5 μg cypermethrin treated glass vials. Mean survivorship (adjusted for control mortality using Abbott's formula) was 31.5%, higher than last year's (2018) average of 26.1%. Additionally,Lygus lineolarispopulations from weedy hosts and commercial cotton fields in Virginia, North Carolina, South Carolina, Georgia, Alabama, as well as a representative population from the Mid-south (Stoneville, Mississippi) were exposed to varying concentrations of insecticides currently being used for Lygus control in the Southeast including sulfoxaflor, imidacloprid, bifenthrin, and acephate. High levels of pyrethroid resistance were measured in Virginia, North Carolina, and Alabama. (2) Replicated small plot experimentswere used to test how insecticides performed in the field. Experiments were conducted in cotton (aphids, bollworm, tarnished plant bug, thrips), peanut (thrips, southern corn rootworm, corn earworm), wheat (aphids), alfalfa (alfalfa weevil), soybean (stink bug, soybean looper), and corn (western corn rootworm, brown stink bug). Resulting recommendations were shared with producers via the Ag Pest and Advisory Blog and Pest Management Guides.

Publications

• Type: Websites Status: Published Year Published: 2019 Citation: Dorman, S., and S. Taylor. Tarnished Plant Bug Management Strategies for Mid-Atlantic Cotton. Plant Management Network (PMN) Focus on Cotton. June 2019. http://www.plantmanagementnetwork.org/edcenter/seminars/cotton/TPBManagementStrategies/
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Dorman, S., R. Sch�rch, A. Huseth, and S. Taylor. Landscape and climatic factors driving spatiotemporal abundance of Lygus lineolaris (Hemiptera: Miridae) in cotton agroecosystems.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Dorman, S., S. Malone, and S. Taylor. 2019. Evaluation of selected foliar broadcast-applied insecticides for management of plant bugs in cotton, 2017-18. Arthropod Management Tests: 44 (1). Doi.org/10.1093/amt/tsz044
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Aghaee, M., S. Dorman, S. Taylor, and D. Reisig. 2019. Evaluating Optimal Spray Timing, Planting Date, and Current Thresholds for Lygus lineolaris (Hemiptera: Miridae) in Virginia and North Carolina Cotton. Journal of Economic Entomology. Doi.org/10.1093/jee/toy407
• Type: Other Status: Published Year Published: 2019 Citation: Britt, K, S. Taylor, and T. Kuhar. 2019. Corn earworm, Helicoverpa zea, a pest of hemp, Cannabis sativa, in Virginia. Virginia Cooperative Extension Publications: ENTO- 328NP.
• Type: Other Status: Published Year Published: 2019 Citation: Balota, M., D. Jordan, H. Mehl, J. Shortridge, and S. Taylor. Insect control in peanuts. 2019 Virginia Peanut Production Guide. Virginia Cooperative Extension Publications: SPES-67NP.
• Type: Other Status: Published Year Published: 2019 Citation: Catron, K., T. Kuhar, and S. Taylor. 2019. Sugarcane Aphid in Virginia Sorghum. Virginia Cooperative Extension Publications: ENTO-334NP.
• Type: Other Status: Published Year Published: 2019 Citation: Dorman, S. and S. Taylor. 2019. Tarnished plant bug. Virginia Cooperative Extension Publications: ENTO-329NP.
• Type: Other Status: Published Year Published: 2019 Citation: Malone, S., S. Taylor, and E. Day. 2019. Aphids in Virginia Small Grains: Life Cycles, Damage and Control. Virginia Cooperative Extension Publications: ENTO-306NP.
• Type: Other Status: Published Year Published: 2019 Citation: Taylor, S. Insect control in field crops. Pest Management Guide: Field crops, 2019. Virginia Cooperative Extension Publications: ENTO-288P.