Spotted Wing Drosophila in Texas

Hosts

Major hosts:
Credits: UMass Amherst

Crop host:

• Apple
• Asian Pear
• Asian Plum
• Blackberries
• Blueberries
• Boysenberries
• Cherries
• Cold Hardy Kiwis
• Elderberries
• Grapes
• Italian Plums
• Mulberries
• Nectarines
• Peaches
• Persimmons
• Plumcots
• Raspberries
• Strawberries
• Tomatoes

Wild host:

Details:

Spotted Wing Drosophila (SWD), Drosophila suzukii, is an invasive pest that was first seen in California in 2008.  Unlike other vinegar flies that typically only lay eggs in fruit that is already rotting/damaged, SWD females have a serrated ovipositor, giving them the ability to lay eggs in fruit before it is ready to harvest.  As a result, fruit can have one or several SWD larvae in the fruit when it goes to market.  If left unmanaged, SWD can result in 80% or more crop loss, depending on the crop and location.  Substantial crop loss due to SWD is yet to be reported in Texas, so growers should be aware of the pest and signs of SWD damage, but do not currently need to develop control strategies.

Males can be distinguished by a spot on the tip of the first wing vein, which can be seen with a trained naked eye.  Identifying a female, on the other hand, requires the use of a microscope to see the ‘teeth’ or serrations on the ovipositor.  The larvae can be seen in the fruit with the naked eye by opening the fruit.  Look for very small maggots, no longer than 1/8 inch.  Infested fruit will tend to be softer and can be more susceptible to fungal pathogens as secondary infestations.

Very simple home-made SWD traps can be made, using apple cider vinegar as the bait.  Samples can be submitted for identification using the Spotted Wing Drosophila Submission Form.  Although SWD has been detected in Texas, no management or preventative measures are currently being suggested for growers in Texas, since there have been no reports of damage or crop loss.