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Why is Spotted Wing Drosophila (SWD) a concern? This invasive
insect primarily attacks blueberries, blackberries, raspberries, cherries,
strawberries, elderberries, and peaches. Less preferred fruits include grapes
and wine grapes, figs, boysenberries, plums, nectarines, and persimmon. Unlike
other vinegar flies, SWD attacks sound ripening fruit and once eggs are laid
inside fruit, insecticides will provide no control. Thus, it is imperative to
control SWD before females lay eggs. Its short lifecycle and overlapping
generations make spray timing difficult. An added problem is that for
successful control farmers need to spray near harvest time and multiple sprays using
the same insecticide class can lead to pesticide resistance. Thus, it is
important to rotate insecticide classes.
Below is a summary of our 2014 experiences
in terms of monitoring tools and an overview of the SWD monitoring approach for
2015.
2014
evaluation of commercial and home-made lures for SWD. From late July to
late October 2014 the LU IPM program conducted a field study aimed at comparing
the attractiveness of a new synthetic lure (trade name: SWD Pherocon, by Trece
Inc.) versus that of the standard yeast / sugar bait (home-made lure) to male
and female SWD. The study took place in an unsprayed elderberry plot at the Lincoln
University Carver farm (Jefferson City, MO). Traps were deployed in pairs (n=
4), about 10 ft. apart, on fruiting plants. Traps were inspected once a week
and all insects captured were taken to the lab for identification. Every week,
the one-week old traps were replaced with traps having new baits / lures.
Key findings: As shown in the
graphs on the right, the active dry yeast + sugar bait consistently
out-competed the new commercial lure.
The table below
summarizes captures across the entire season. It reveals that the standard sugar
/ yeast bait was on average 4.8 and 20.3 times more attractive to males and
females, respectively, than the new lure. 
Monitoring
for SWD in 2015.
The first adult Spotted Wing Drosophila was captured by a monitoring trap in
the Jefferson City area on May 27th, 2015. This trap was hung from a
mulberry tree that has ripening fruit. Since then, SWD has been found in most
locations where SWD monitoring traps have been setup by the LU / MU IPM
programs. Consequently, farmers are encouraged to monitor for this insect pest.
Ideally, monitoring traps should be
deployed starting 3-4 weeks before berry
ripening and throughout the
harvest season. Place one monitoring trap baited with active dry yeast (1/2
tablespoon), sugar (2 tablespoons) and water (6 ounces) per acre. The trap
needs to be hang on a plant, stake, or trellis 3–5 feet above the ground on the
most shaded / cooler side of the plant canopy. Because SWD reproduces so quickly under warm weather conditions, the
first SWD trapping data are vital to activate pest management programs to
prevent rapid population increases and potential infestations on a farm.
For 2015, the Lincoln University and the
University of Missouri IPM programs will be monitoring the presence and
abundance of SWD in selected locations throughout Missouri. Information will be
posted weekly at the MU IPM Pest
Monitoring Network website.
SWD
Management for the 2015 season. Farmers are advised to apply an
insecticide as soon as SWD is detected and fruit is at susceptible stage.
Cultural controls such as sanitation (i.e., clean up and destroy over-ripe
fruit) and pruning to reduce amount of foliage can help reduce breeding sites
and can also improve insecticide coverage. Articles discussing the importance
of SWD monitoring, how to make your own monitoring trap, management option
including organic tools can be found at: http://www.LU-IPM.net. Note that the
Spotted Wing Drosophila tab has a scroll down menu. Fact Sheets and Guide
Sheets listing the most effective organic and reduced-risk insecticides that
can be applied against SWD are available the LU IPM program
website.
By Dr. Jaime Piñero - Lincoln University (LU) IPM
program
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