Location: Horticultural Crops Research
Project Number: 2072-22000-044-15-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2020
End Date: Oct 31, 2021
1. Investigate non-target effects on Spotted-Wing Drosophila (SWD) natural enemies and honeybees. 2. Examine the efficacy of the new formulations in the field for reducing SWD infestation, while monitoring visitation rates by honeybees and impacts on fruit quality.
Objective 1 - the trial will monitor the longevity of wasps fed solutions in a vial to confirm impacts, and with solutions on sprayed fruit to reflect what would wasps would encounter in the field, fruit with residues. At least 30 female and 20 male wasps will be tested in each treatment combination. A second trial will test longevity in a similar setup with wasps given floral nectar or wounded fruit together with treated fruit. This reflects what may occur in the field; wasps may have access to other sugar sources along with the sticky residues on sprayed fruit. Small hive boxes in large cages will be placed with flowers and blueberries sprayed with a treatment. Honeybees have a foraging radius of 2 miles and likely encounter multiple sugar sources. The hives will be checked weekly for larval mortality, and development tracked until adulthood. Each treatment will be replicated 4 times over the summer. Objective 2 - At an experimental farm, blueberry plants will be sprayed once they start ripening with one of three solutions. Plots will contain 8 plants per row, separated by at least 30 m, and replicated 4-5 times. Each week, plots will be monitored for the presence of SWD adults in baited traps, and for larval infestation by collecting and rearing 2 kg of fruit per plot. Spray volume to fully cover plants will be recorded and canopy size measured. Each week, honeybees, yellow jackets and other sugar feeding insects seen foraging on the bushes will be observed. Passive sticky traps will be placed 4 per plot to count honeybees. A similar analyses will compare honeybee presence, and whether visitations lessen as the sugar wears off over time. Each week, we will scan blueberry plants in each plot for visible signs of phytotoxicity, Botyrtis, Powdery mildew, or other abnormal appearances on leaves and fruit. Fifty random fruit per plot will be collected to measure the size, firmness, Brix and pH. In addition, five red raspberry, blackberry, and strawberry 4-plant set will be sprayed per treatment to assess impacts on a wider variety of small fruits.