Project Overview
Spotted-wing drosophila (SWD) is a major economic pest of fruit crops like berries, notable for consuming fruit early in the ripening stage. At present, the most effective controls for spotted-wing drosophila involve broadcast or airblast applications of insecticides, with limited options (i.e., spinosad) for organic growers. Alternative (non-insecticidal) management practices are important when establishing pest management plans, as they can reduce the emergence of insecticide-resistant pests, pesticide exposure for farmworkers and consumers, and secondary pest outbreaks.
One alternative management practice for spotted-wing drosophila involves attracting insects towards a specific site where they can be exposed to a targeted dose of insecticides. This attract-and-kill approach typically uses attractants such as pheromones or baits in a gel matrix, bait station, or similar material that is placed away from sensitive plant tissues. Placing the insecticide along with the attractant can potentially reduce the amount of applied insecticide while keeping insecticide residues away from the crop and improving efficacy of the treatment.
Researchers in Florida and Georgia tested different combinations of gel attractants and organically-approved insecticides, including spinosad and alternatives, for their efficacy in protecting blueberries against spotted-wing drosophila in a series of lab and potted plant experiments.
Farmer Takeaways
- The attract-and-kill approach shows some potential against spotted-wing drosophila (SWD), and gel attractants with spinosad and pyrethrins caused significant insect mortality in lab tests.
- When tested at a larger scale on potted blueberry plants in small cages, the attract-and-kill approach was not effective at reducing SWD populations with any insecticides, including spinosad and pyrethrins.
- Attract-and-kill has potential against SWD, but it needs refinement to be effective as a standalone management practice. It should be considered as part of an integrated pest management program, alongside other pest management practices.
Project Objectives and Approach
Assess the attract-and-kill approach for managing spotted-wing drosophila in blueberries using lab and small-scale field assays
- Researchers at the Universities of Florida and Georgia developed a series of experiments to test whether spotted-wing drosophila can be attracted away from blueberries using a specially-formulated gel attractant material. This gel attractant would be mixed with different insecticide active ingredients to kill spotted-wing drosophila while keeping them off the crop.
- In a lab study, the researchers placed a short stem with three to four young leaves from a blueberry plant into a small container with 13-15 commercially-grown, organic blueberries. The researchers placed a small drop of the gel attractant mixed with various insecticides (see below) onto a leaf, before adding 10 adult spotted-wing drosophila and sealing the container. After seven days, the researchers counted insect mortality and removed the berries to incubate and allow any drosophila eggs to hatch.
- In a field study, the researchers placed individual potted two-year-old blueberry plants into cages covered in fine mesh. The researchers applied the insecticidal gel attractant to plastic strips, which they then affixed to the blueberry stem. The researchers also attached blueberry clusters around the blueberry bush, inside the cage. Then, 50 mature spotted-wing drosophila were introduced to each cage for 24 hours before the insecticidal attractant lures and berry clusters were removed and remaining living spotted-wing drosophila were counted.
Compare the efficacy of different organic insecticides in the attract-and-kill approach
- A major focus of the project was to identify potential organically-acceptable alternatives to spinosad. The researchers evaluated gel attractants with several different insecticides, including active ingredients that are already available and still in development.
- In addition to spinosad, these insecticides included pyrethrins, azadirachtin+pyrethrins, formulations containing Chromobacterium subtsugae bacteria, and formulations containing Burkholderia rinojensis bacteria.
Key Findings
Pyrethrins and spinosad both increased spotted-wing drosophila mortality in the lab experiment
- Pyrethrins and spinosad were both effective at reducing spotted-wing drosophila populations in lab tests, reducing populations by about 60% to over 90% on average over seven days. Spinosad was somewhat more consistent and faster acting.
- Other tested insecticides were not effective, which highlights the importance of understanding the mechanisms by which spotted-wing drosophila interact with insecticides and gel attractants.
The attract-and-kill approach did not control spotted-wing drosophila in caged plant assays
- In the caged plant assays, none of the insecticides consistently increased spotted-wing drosophila mortality or decreased insect counts in fruit compared to non-treated controls.
- Larger scales and longer timelines can increase variability in spotted-wing drosophila survival. Under this increased variability, insecticide treatments have to have a stronger effect in order to be effective.
- This research is consistent with attract-and-kill trials using conventional insecticides, where they may be effective in the lab but less so when scaled up. Attract-and-kill techniques are still under development and would be most effective as one component of an integrated pest management program.
Resources
Rhodes, E. M., Babu, A., Sial, A. A., & Liburd, O. E. (2023). Potential Alternatives to Spinosad as the Killing Agent Mixed With Two Attractant Products in Attract-and-Kill Formulations Used to Manage the Spotted-Wing Drosophila, Drosophila suzukii (Diptera: Drosophilidae). Journal of Economic Entomology, 116(1), 202–208.
Read MoreLocation
Florida, GeorgiaCollaborators
Arun Babu, University of Georgia
Ashfaq Sial, University of Georgia
Oscar Liburd, University of Florida
Region
Southeast
Topic
Insect/Pest Management
Category
Vegetables/Fruits
Year Published
2023
