Thesis
A soil temperature degree-day model for the alkali bee (Nomia melanderi)
Washington State University
Master of Science (MS), Washington State University
05/2020
DOI:
https://doi.org/10.7273/000004093
Handle:
https://hdl.handle.net/2376/125310
Abstract
In Washington State's Touchet Valley there are over 2,400 ha of alfalfa grown for seed. In these fields, there are three managed bee species utilized for pollination services. Of the three species, the ground-nesting alkali bee, Nomia melanderi, is the most efficient pollinator, pollinating up to 90% of flowers visited. When soil temperatures rise in the spring, alkali bees break dormancy and begin adult development, typically emerging in May. However, to control the key direct pest, Lygus hesperus, most alfalfa seed growers apply a broad-spectrum insecticide in late spring. If bees emerge in late spring during insecticide application, there is risk for high bee mortality. Integrated pest management tools are then needed to improve timing of insecticide applications for Lygus control while preserving alkali bee populations. The objective of this study was to develop soil temperature-based phenology models to better predict alkali bee emergence. Soil temperature loggers were buried below the soil in April 2018 and 2019, at six alkali bee-beds in the Touchet Valley. Studied bee-beds were surveyed twice a week from late May through mid-June to track emergence rate of the alkali bees. Soil temperature data was used to calculate cumulative soil degree-days and regressed with emergence rates to quantify the relationship of heat accumulation to initial date of emergence. This study found that cumulative soil degree-days were positively correlated to alkali bee emergence. This soil temperature-based model will assist alfalfa seed growers by improving their timing of late spring insecticide sprays to reduce alkali bee exposure risk.
Metrics
Details
- Title
- A soil temperature degree-day model for the alkali bee (Nomia melanderi)
- Creators
- Greta Dupuis
- Contributors
- Doug Walsh (Advisor) - Washington State University, Department of Entomology
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Entomology
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900890787301842
- Language
- English
- Resource Type
- Thesis