First capture of spotted wing Drosophila in Michigan for 2013

Early capture of spotted wing Drosophila emphasizes the need for monitoring and preparing for fruit ripening period.

A single female spotted wing Drosophila (SWD) was collected in a trap checked on June 6, 2013, in Michigan’s Allegan County. This fly was found in a yeast-sugar baited trap at a tree line adjacent to a commercially-managed blueberry field. The timing of this capture is about two weeks later than our first catch in 2012, reflecting the cooler spring season. Also, as part of our research on SWD, there are a large number of traps in the region where this fly was found, so we have a very low proportion of traps catching this pest (about 1 percent of traps). In the previous few years of our experience with SWD, there were low captures for many weeks before the population increased when fruit became ripe. It is too early to tell how this will look for 2013.

Most fruit fields and orchards are still with green fruit, meaning that SWD cannot yet infest berries, so for most fruit growers there is no need to spray insecticides for control of this fly yet. For strawberry growers who do have ripe fruit, monitoring those fields and checking ripe berries for larvae should be a first step before taking any action as the numbers of SWD are currently extremely low. However, this can be considered an early warning that SWD is starting to become active and that monitoring programs should be in place to determine when SWD becomes active in different regions and in your farm. Michigan State University Extension has a monitoring network in place across the major fruit production regions and we will be reporting those catches weekly as part of the MSU Extension Fruit News.

If you are checking traps, be aware that the female SWD that have no spots on the wings look quite similar to a native vinegar fly that could be confused with SWD. See the MSUE News article “Spotted wing Drosophila monitoring should be started soon – know what to look for” for a good photo of the look-alike next to SWD.

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