Spotted wing Drosophila
Spotted wing Drosophila

University of Florida researchers are looking for Integrated Pest Management (IPM) approaches to control a destructive pest of Florida small fruit crops.

Entomology graduate student Lindsy Iglesias, along with professor Oscar Liburd, are using a $10,837 Southern Sustainable Agriculture Research and Education (SSARE) Graduate Student Grant to develop an IPM program to manage the spotted wing Drosophila (Drosophila suzukii) – a vinegar fly related to the common fruit fly.

"Unlike the fruit fly, which is just a nuisance, the spotted wing Drosophila is considered an invasive pest and an important agricultural pest of berries and stone fruits," said Iglesias. "This pest is particularly destructive because unlike most other vinegar flies which solely lay eggs on rotting fruit, this fly will lay eggs in healthy, ripening or maturing fruit. The larvae that hatch out feed on the fruit, basically making the crop unmarketable."

The spotted wing Drosophila arrived in the United States from Asia in 2008 and has spread across the Southeast. It showed up for the first time in Florida in 2009. The females use a serrated egg-laying structure to puncture the fruit's thin skin and lay several eggs inside the fruit. It only takes a few days for the larvae to hatch and begin feeding on the crop. Iglesias said that it's not uncommon for several females to lay claim to one fruit, dramatically increasing the number of larvae that can attack the crop.

"It's generally recognized that the economic threshold of the pest is one," said Iglesias.

Currently, some chemicals are available to control the pest, and growers are also encouraged to apply cultural control methods, such as frequent harvest intervals and crop sanitation (picking up dropped fruit to prevent additional habitat sources). But Iglesias is interested in expanding grower options.

In the SSARE-fund study, Iglesias is targeting alternative IPM methods in blueberries because they appear to be most affected by spotted-wing Drosophila feeding and damage. In Florida, blueberries are among the top four small fruit crops, along with strawberries, grapes and blackberries.

"Through this project, we are hoping to pull out techniques that can be applied to not only blueberries, but to other small fruit crops, and be relevant in other states, not just Florida," said Iglesias.

In the project, Iglesias is conducting four major IPM techniques: 

  1. Distribution. Researchers hope to identify where the pest is located within Florida by setting traps in 15 farms from as far north as Suwanee County to as far south as DeSoto County. "As soon as the berries begin ripening, we plan to put out traps with apple cider vinegar as bait," said Iglesias. "From there we hope we can identify where the flies are potentially coming from." For now, said Iglesias, researchers are not sure what is the pest's overwintering host and how it migrates from one area to another.
  2. Monitoring. Using a trap and lure system, researchers plan to experiment with various types of baits – apple cider vinegar, wine, sugar/yeast mixture -- to determine what the fly is most attracted to. "We want to see if there are any differences in the baits chosen, and what it is about a specific bait that the fly is attracted to," said Iglesias. Both lab studies and field research will be conducted.
  3. Trapping. "We want to determine what visual sensory characteristics, such as shape and color, attract the pest to the plant crop," said Iglesias. Researchers plan on using various shaped traps, vertical stripes and the color yellow as visual stimulators.
  4. Egg laying behavior. "The spotted wing Drosophila prefers ripening fruit, but will lay eggs in damaged fruit if nothing else is available," said Iglesias. "If we can identify susceptible blueberry varieties, or determine the susceptibility of the fruit's ripening stages, it may help the grower choose cultivars that control pest populations, or implement techniques such as buffers that disrupt pest distribution."

Researchers plan to extend the results of the research to growers, Extension agents and industry representatives during meetings and trainings.

"One of our goals is to train growers on spotted wing Drosophila identification in the field," said Iglesias. "We also plan to provide additional IPM techniques to growers to help them control spotted wing Drosophila in their fields and help protect their crops."

The two-year project, "Developing an Integrated Pest Management Program for a Newly Introduced Pest in Florida Blueberries: The spotted wing Drosophila (Drosophila suzukii)," will begin in early 2013.