Spotted Wing Drosoplila

The Cornell University College of Agriculture and Life Sciences publishes a scientific newsletter called the New York Berry News. These newsletters publish a variety of articles relating to berries and berry production including topics like: frost protection, post-harvest care, organic farming, pests and diseases, etc. I found the newsletter of great interest because of the wide diversity of topics all related to berries and creating healthy berry habitats whether wild or cultivated. Although most of these articles are mostly concentrated on berries growing in the New York State area, I found that much of the information given can be used as helpful tips and guides for growing and managing berries here in Alaska. One of the articles I found interesting is about the Spotted Wing Drosophila (SWD).

The Spotted Wing Drosophila (SWD) is an invasive small fruit fly that is a major pest problem for raspberries, blackberries and other cane berries as well as blueberries, strawberries, grapes and other small fruits and berries. The SWD is originally native to Asia but in 2008 the first confirmation of SWD was found in California (Wold-Burkness & Hahn) and since then has spread throughout most of the fruit growing regions in the United States. Found in New York State in 2012, the SWD has caused serious crop losses in every year since (Wallingford & Loeb).

The SWD is a small fly that typically measures only about 2-3mm long, has big red eyes and a yellow/brown body (Wold-Burkness & Hahn). The abdomen has small rings around it and large clear wings. They are hard to identify against other small fruit flies, but the males do have a large black spot near the top and back half of their clear wings (Wold-Burkness & Hahn). The SWD larvae are commonly called maggots and have small tubular shaped bodies with no legs.

The adult SWD inserts its eggs under the skin of young fruit both wild and cultivated. In New York the SWD populations are relatively low during the spring months, but as fruit begins to ripen and berries are in large abundance the populations are also in large concentrations and this is why so many berry crops are suffering (Wallingford & Loeb). The adult SWD flies feed on thin skinned soft fruit such as berries, grapes, and plums. The larvae will feed on the fruit under the skin and cause the fruit tissue to be browned and squishy. Sometimes the damage to the fruit that the larvae produce will go unnoticed until after harvest and can be seriously detrimental to harvest production.

In New York pesticides are used in effort to control SWD populations but often weekly doses are needed to keep infestation levels down (Wallingford & Loeb). Weekly insecticide applications can be expensive and also damaging to the plants health and production rates and many growers are experiencing “sprayers fatigue” (Walligford & Loeb). In addition to the damage the flies cause and the damage from over spraying of pesticides, these flies can make the plants more susceptible to infestation by other insects, rot fungi and diseases (Wold-Burkness & Hahn).

There are currently many studies on the SWD and their effects on fruit production including studies relating to growth cycles, winter/cold survival, organic pest control, cultivating techniques, etc. These are relatively new pests in the United States and although I cannot find anything confirming their existence in Alaska, it seems that it is only a matter of time before we are also actively battling the Spotted Wind Drosophila. If you are looking for more information about the SWD I have attached both the New York Berry News article as well as a study conducted by the University of Minnesota Cooperative Extension Program. LH Fairbanks

Wallingfor, A. and Loeb, G. 2016. Spotted Wing Drosophila: Winter Biology. New York Berry News. 15 (2): 5-18. Available online: http://www.fruit.cornell.edu/nybn/newslettpdfs/2016/nybn1502.pdf Accessed: 10 Oct. 2016.

Wold-Burkness, S. and Hahn, J. 2016. Spotted Wing Drosophila in Home Gardens. Insects. University of Minnesota, Extension. Available online: http://www.extension.umn.edu/garden/insects/find/spotted-wing-drosophila-in-home-gardens/ Accessed: 10 Oct. 2016.

 

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