Recipient Organization
WASHINGTON STATE UNIVERSITY
240 FRENCH ADMINISTRATION BLDG
PULLMAN,WA 99164-0001
Performing Department
Agricultural Research Center
Non Technical Summary
Our multi-state (Washington, Idaho, California), multi-institutional (WSU, UI, UC) research and extension team proposes to conduct research and outreach to improve pollination services while simultaneously preserving and protecting key managed pollinators, enhancing the abundance of endemic pollinators, and reducing the risk imposed by Lygus bug feeding injury to high-value Western U.S. alfalfa seed grown as a non-food/non-feed crop. Pollinator safety has become the greatest barrier against registering reduced-risk pesticides on alfalfa produced for seed. The key direct pest of alfalfa produced for seed (Lygus bug) reaches its greatest population abundance concurrent with alfalfa bloom when key managed and endemic pollinators are actively completing pollination services in fields of alfalfa produced for seed. We will create a matrix of insecticide chemistries and insect susceptibility that reflects pest vulnerability as well as safety to non-target pollinating arthropods as a risk-reduction tool. We will also quantify the pesticide exposure rates on beneficial pollinators and qualify how these exposures affect biology and behaviors of managed pollinators. We also seek to improve overall endemic pollinator health and abundance to increase alfalfa seed yields. We will disseminate educational outreach materials in a multi-modal, timely, and targeted fashion appropriate to relevant state-based and regional alfalfa seed grower groups. Our project evaluation plan includes both qualitative (focus group) and quantitative (survey) annual stakeholder input.
Animal Health Component
65%
Research Effort Categories
Basic
35%
Applied
65%
Developmental
(N/A)
Goals / Objectives
In order to ensure the availability of pest management tools in alfalfa produced for seed, pollinator health must be considered side-by-side with pest control efficacy. We propose a multi-pronged approach to improve pollination services in alfalfa seed fields, thereby paving the way for more options in pest control.Create a matrix of insecticide chemistries and insect susceptibility profiles that reflects pest susceptibility and safety to non-target predatory, parasitic, and pollinating arthropods.Develop and validate new techniques to assess the sublethal effects of flonicamid, flupyradifurone, and sulfoxaflor pesticides on alfalfa leafcutting bee foraging behavior, and determine the impact of the new candidate pesticides on bee return.Measure the pesticide residue concentrations found in pollen in brood cells from fields sprayed with flonicamid, flupyradifurone, and sulfoxaflor during bloom.Determine the impact of pesticide load on development in leafcutting bee brood.Test a novel method for enhancing populations of soil-nesting bees by identifying the nesting bee species and quantifying the change in bee emergence rate achieved by irrigating soil at field margins.Disseminate educational outreach materials to alfalfa seed growers and other stakeholders.Conduct annual project evaluation with focus group to quantify project value and impact.
Project Methods
We will conduct pesticide rotation trials using materials registered for use on alfalfa grown for seed. Efficacy will be evaluated by sweep net sampling. Impacts on beneficial arthropod populations will be assessed. Registered and candidate chemistries will also be evaluated on field-caught and laboratory-reared beneficial arthropods using a Potter spray tower. Field-aged residues of registered and candidate chemistries will be evaluated for effects on pollinators. A matrix of insecticide chemistries and insect susceptibility profiles that reflects pest susceptibility and safety to non-target predatory, parasitic, and pollinating arthropods will be created.Toassess sublethal effects of new pesticides on alfalfa leafcutting bee (ALCB) foraging behavior, we will establish large field plots in the Touchet/Lowden alfalfa seed-growing region of Walla Walla County, WA, each with 9+ALCBdomiciles. Experimental Use Permits will be obtained if necessary. New selective compounds flupyradifurone and sulfoxaflor will be compared with the current grower standard tank mix (naled+flonicamid). Fields will be divided into three experimental treatments that will be sprayed at night at the maximum permitted concentration. Two hours of video will be taken with Mobius cameras during the ALCB active period on the morning of the spray, the next day, and 3 days following the spray. A nearby field that has not been sprayed in at least a week will be used as a control. Behaviors will be compared between bees in domiciles in fields treated the evening before with candidate insecticides, and bees in domiciles in fields that had not been treated with insecticides for at least one week. Behaviors quantified will include the number and duration of pollen and leaf forage trips, and time spent in the provision hole.To determine the impact of the candidate pesticides on bee return, 8 research binder boards will be placed in each of 9 domiciles among the 3 treatments. Four boards will be used for residue analysis and the rest will be x-rayed to assess larval development. Paper straws will be placed in each nesting hole. The boards will be placed in the domiciles prior to the initiation of Lygus insecticide sprays. At the end of bloom,boards will be removed and transported to WSU Prosser, wherethe paper straws will be x-rayed. X-rays will be evaluated for proportion of cells with healthy larvae compared to cells with parasitized larvae or undeveloped cells. Undeveloped cells will be dissected to distinguish pollen balls (cells where no egg was deposited) from cells with dead eggs or early instar larvae. To assess sex ratios and bee return, cells with healthy larvae will be overwintered with a grower and incubated in the spring.We will also place research binder boards in the fields to be colonized by foraging females. A subset of provisioned brood cells will be removed just prior to insecticide application. Some boards will be sealed prior to insecticide treatment, while others will be exposed to treatments and removed from the field 2 days later and still others will be left in the field for the rest of the season. All subsets of brood cells from the various treatments will be evaluated for residues of the subject pesticides by LC-MS/MSto determine if there is a link between brood cell insecticide load and the pollen ballphenomenon.To determine impact of pesticide load on development of ALCB, we will purchase loose bees and place them in domiciles in pristine locations. We will remove developing bees from the boards weekly during peak bloom and evaluate their stage of development on a numerical scale. Developing bees will be exposed to varying concentrations of candidate pesticides and the cells held through early August, at which time they will be x-rayed and cohorts of properly developed pupae, improperly developed pseudopupae, and pollen ball provisions will be sent to the IR-4 TAL to quantify pesticide loads. Statistical analysis relating insecticide residue load against bee development will quantify the potential relation between bee development and insecticide exposure.To investigate a novel method for enhancing populations of soil-nesting bees, we plan to manipulate soil irrigation and quantify the resulting change in bee emergence rate. Most growers of alfalfa for seed have access to pressurized water in the field. We propose to run 5 cm dia. schedule 40 PVC pipe along the margin of 4 fields for 400 m at each field. This pipe will be buried at approximately 15 cm. Every 25 m, we will attach a riser to deliver water to the surface. We will fabricate attachments onto which we will attach lengths of 1.9 cm polyethylene tubing with drip emitters inserted at 0.5 m intervals. Three types of pressure-compensating emitters will be tested. These will include emitters that will deliver 1.9 l, 3.8 l, and 7.6 l per hour. Control plots will be 25 m segments that remain non-irrigated. Each treatment will be replicated in four 25 m replicates in the 400 m length. In the establishment year of 2017, colonization and establishment will be made by direct counting of nesting holes created in row by treatment at 2-week intervals through June, July, and August. Four emergence cages consisting of 30 cm diameter PVC rings capped with screen will be placed out each spring in mid-May. These cages will be checked weekly between mid-May and mid-June and the number of insects in each cage will be counted weekly and released. Totals will be calculated at the end of the growing season. To assess the abundance of bees foraging in the field, 4 transects perpendicular to irrigation will be established in each of the four fields. These transects will be sampled using previously validated white bee bowl traps placed on the field edge and at 10, 20, 30, 40, and 50 m into the field. The bee bowls will be filled for one 24-hour period each week from mid-May through early July with a 200 ml of a 4:1 mixture of water and propylene glycol. Bees captured in the field will be filtered out and transferred to tubes of 85% ethanol. The propylene glycol solution will be recycled and used all season. A similar set of transects will be established on the other side of the field where no plots with drip irrigation have been established to determine if differences in the abundance of Agapostemon spp. and other ground dwelling bees is observed.Our educational outreach plan includes electronic and printed materials (e.g., handouts/fact sheets, Extension Bulletins, Pacific Northwest Pest Management Handbook content, website content).Project evaluation includes qualitative input from afocus group and quantitative input from a survey, both deployed annually at the Western Alfalfa Seed Growers Association in January.