Rushville Republican

August 23, 2013

Invasive Fruit Fly Could Devastate Franklin County Berry Harvest


Rushville Republican

RUSHVILLE — The spotted wing drosophila has been positively identified in Franklin County by the Purdue Extension Office in Brookville. Anna Morrow, Franklin County’s Ag and Natural Resource Educator, answered a call concerning small white worms in blackberries that were only noticeable when the fruit was cooked. The blackberry canes and berries appeared normal, until the client went to make jam from the berries.

Research into the matter led me to believe that this was spotted wing drosophila. Spotted wing drosophila (SWD) is an invasive pest native to Asia, which was first detected in North America in California during 2008. SWD was first detected in Indiana last fall by the Purdue Extension Office in Blackford County.

SWD cannot be positively identified by larva alone and so I needed to trap adult flies to confirm that Franklin County was indeed dealing with SWD. Traps made out of plastic cups using apple cider vinegar for bait caught several fruit flies. These flies were sent to Purdue and identified by an USDA-APHIS (US Department of Agriculture – Animal and Plant Health Inspection Service) insect identifier.

SWD are particularly harmful to small fruits because they are able to lay eggs in intact fruit, unlike native fruit flies. Soft skinned fruits such as blackberries, raspberries, and blueberries are at higher risk for SWD. Female SWD make a tiny cut into fruit that is just beginning to color and lay their eggs inside the fruit during late summer. As the fruit ripens, the eggs hatch and larvae eat the fruit. It is nearly impossible to tell if eggs have been laid inside the fruit until the larvae have done their damage. SWD will also lay eggs in strawberry, cherry, and grapes.

Cultural control of this pest includes removing and destroying overripe fruit to prevent larvae from developing into adults. Removing wild host plants that can harbor SWD such as wild grape, pokeberry, honeysuckle, nightshade, dogwood, spicebush, autumn olive, raspberry, and blackberry may also help control SWD. There are several registered conventional insecticides that are affective against SWD. For recommendations, or more information contact Anna Morrow at (765) 647-3511 or by e-mail at annamorrow@purdue.edu. Remember to always read and follow label directions.

This is another way that the extension office is working to inform Franklin County residents of important issues. The identification of this new and worrisome pest was made as part of a routine call to the extension office. If you suspect an invasive pest, or have other ANR questions, please contact the extension office.