NOVEL APPROACHES FOR PEST MANAGEMENT AND POLLINATOR PROTECTION DURING THE PRODUCTION OF ALFALFA GROWN FOR SEED

Effective and efficient control of insect pests remains one of the major concerns for the agricultural industry. Growers' reliance on insecticides is nowhere more apparent than in alfalfa grown for seed. With recent concerns regarding insecticide resistance and off-target effects of insecticides on beneficial species, alfalfa seed growers are facing increasing pressure to effectively manage and protect commodities in all aspects of their farming operation. The goals of this project will be expanding availability of reduced-risk, selective insecticides to protect pollinators and other beneficial arthropods, along with developing new integrated pest management strategies for the continued sustainability of alfalfa grown for seed.For optimized production of alfalfa grown for seed, proper control of arthropod pests and pollinator health must be considered side-by-side. With the current restrictions and expected future loss of insecticide chemistries (organophosphates including chlorpyrifos) to control arthropod pests in alfalfa, growers are facing an uphill battle and uncertainties for production. We propose a multi-pronged IPM approach that encompasses four research objectives and two Extension/learning objectives that will generate new integrated pest management strategies for the control of the primary pest in this production system, Lygus bug. Proposed strategies will also prioritize the protection of pollinators (essential to seed production) and other beneficial arthropods (a vital part of Lygus control).Objective 1: Test chemical alternatives for Lygus bug control without the use of chlorpyrifos. We will examine both registered and unregistered but commercially viable insecticide compounds for their efficacy against Lygus bugs, as well as optimize timing and rates of insecticide application. This will be completed using a combination of both field and laboratory studies.Objective 2. Test the establishment of physical barriers to prevent adult migration of Lygus from fields of alfalfa produced for forage into fields of alfalfa produced for seed. This simple but effective method has been demonstrated to reduce the migration of pentatomid stink bugs in orchard systems in Washington State (Marshall 2020) and from forage alfalfa into cotton in the Southwest. By erecting temporary barriers when alfalfa forage hay is swathed, we may prevent a substantial number of Lygus adults from migrating into alfalfa seed fields. An additional benefit is that we will be able to quantify the migration of other beneficial, pest, or benign arthropods when they are captured in these passive barrier traps.Objective 3: Develop IPM strategies to increase efficacy of biological control measures for Lygus bug control. We will measure the efficacy of commercially available biological control measures including Anaphes spp. (parasitic wasps) and entomopathogenic fungi Beauveria bassiana, Isaria fumosorosea, and Metarhizium brunneum, all of which have been suggested as biorational and useful pathogens for Lygus bug control. We will also test the safety of selective versus broad-spectrum insecticides for natural enemies.Objective 4: Determine the safety for alfalfa leafcutting bees of insecticides useful for Lygus bug control. We will measure the sublethal effects from multiple insecticide chemistries used for Lygus bug control on alfalfa leafcutting bees, the most important managed pollinator in alfalfa seed production systems in the western region.Objective 5: Complete a comprehensive annual survey to provide insight on Integrated Pest Management practices employed to control problematic insect pests of alfalfa while protecting pollinators and other beneficial arthropods. Developing an appropriate integrated pest management program can be complicated and has become even more challenging as chemistries become unavailable. We will annually survey alfalfa seed producers regarding the timing of pesticide inputs, pollinator management, and production guidelines and analyze this information toward developing best management practices to be used in alfalfa seed production. The development and focus of this survey and subsequent analyses will be guided by grower stakeholders. This information will flow directly into Objective 6.Objective 6: Conduct an annual project evaluation with a focus group to quantify project value, assess grower behavior change, and pilot the subsequent year's research priorities based on project performance. Where the aforementioned survey in Objective 5 is largely quantitative, collecting many data points from a large number of growers, this follow-up objective is qualitative in nature, involving in-depth discussion with a highly engaged subset of stakeholders.