Spotted Wing Drosophila - What is it and should I be concerned?

Friday, July 27, 2012

Hi folks,  I hope everyone is having a good season so far and I'm sure everyone is thankful for the rain this week (not only for the cranberries but for our gardens and lawns as well!). 

I am sure most of you have heard of Spotted Wing Drosophila (SWD) - it is a relatively 'new' pest of fruit that was first detected in Ontario in 2010.  It is an invasive vinegar fly of asian of origin that has the potential to cause damage in many fruit crops.  Unlike most vinegar flies that prefer over ripe, damaged or dropped fruit, the SWD female has a serrated ovipositor that allows her to saw through intact fruit and lay her eggs just below the skin.  The larvae then hatch, feed and render the fruit unmarketable.  This oviposition hole can also be a pathway for diseases to enter the fruit causing even further damage.  Generally they only attack 'soft' or thin skinned fruit but there is a possibility they could also attack cranberry.  Last year although detected in NS, they never reached damaging levels in any of the crops, however with the early spring and hot summer we've been having, it's expected that they will be detected earlier this season.  Although Cranberry was not included on the list of emergency registrations for this pests a number of the products that were granted an EUR registration are currently already registered on cranberry for other pests.  These include Entrust, Delegate and Malathion.  

There is an ongoing trapping program in a number of different crops in Nova Scotia and when/if we start to see trap catches we will be posting updates on all of the fruit blogs and let you know if we think population levels are reaching potential problem levels. 

If you would like to read more about spotted wing Drosophila please click here for a factsheet from Omafra and here for an article from Dave Yarborough about the potential for this pest in cranberries.