Cornell Cooperative Extension of Chautauqua County has confirmed a new fruit pest, Drosophila suzukii, the spotted wing Drosophila, in the town of Chautauqua. Spotted wing Drosophila is an invasive pest of Asian origin that was first detected in the continental United States in California in 2005 and has since spread to several western and eastern states. It was first reported in New York in 2011.
Last week, a homeowner from the town of Chautauqua contacted the Master Gardener Helpline at the CCE office regarding an abundance of maggots in her late season blueberry crop. Master Gardeners followed up on this report to confirm the identity of this new pest on Aug. 21.
Spotted wing Drosophila looks similar to small fruit flies found on overripe bananas, which are more of a nuisance than a serious economic threat to fruit growers. However, unlike these other flies, which typically feed on overripe or deteriorating fruits, spotting wing Drosophila feeds on healthy, ripe, marketable fruits leading to damage and contamination with maggots.
Pictured at top is the spotted wing Drosophila which has been found in the town of Chautauqua.
"The problem with these flies are that you won't really know that you have a problem until you go to pick your (fruits)," said Betsy Burgeson, master gardener program coordinator for the Cornell Cooperative Extension of Chautauqua. "When you pick your fruits, they will be soft and fragile. If squeezed, larvae will usually come pouring out. Unfortunately, usually by the time you've found them, it's already too late."
In particular, spotting wing Drosophila will feed on thin-skinned, soft fruits such as raspberries, blackberries, blueberries, strawberries, grapes, plums and cherries. Sometimes the symptoms won't show until after the fruits are harvested and sometimes not until the fruits are in possession of the consumers. In addition to the damage caused directly by the larvae, the feeding makes the fruits susceptible to infestation by other insects, rot fungi and bacteria. The larvae will then leave the fruits to pupate and later emerge as adults.
There is potential for significant impact from this pest, especially for mid-summer and later-maturing fruit, when populations tend to increase. Risk of marketing fruit contaminated with spotting wing Drosophila larvae is high resulting in rejected shipments and consumer complaints. In areas where spotting wing Drosophila has been established longer (e.g. Michigan) some growers have resorted to frequent pesticide applications thereby increasing economic and environmental costs as well as potentially disrupting established IPM programs.
The spotting wing Drosophila is a small fly, only 2-3 mm long, with yellowish brown coloration and prominent red eyes. Male spotting wing Drosophila have dark spots on the wing tips. Spotting wing Drosophila larvae are white with a cylindrical body that tapers on both ends. The adult flies are difficult to distinguish from other small flies; however, if you find an abundance of small, white maggots in what were apparently healthy fruits at the time of harvest, contact the Chautauqua County Cornell Cooperative Extension offices.
"Once they've infested your crop, the only thing you can do is pick any ripe or ripening berries and destroy them," said Burgeson. "You need to either bury the fruit two feet underground or you need to put all your berries in ziplock bags (to suffocate the larvae). Heating up the ziplock bags to a temperature which would kill insects speeds the process along. Putting infected berries in compost is not a good idea, as it will help the larvae mature into flies. The best course of action right now is to destroy all of your good crops, unfortunately."
Monitoring and early, ongoing management is very important for this pest. Traps baited with vinegar have proven successful in capturing sometimes large numbers of adult spotting wing Drosophila. Traps should be frequently checked, adding fresh vinegar. Research is ongoing to improve trap efficiency and develop a better early warning system. Fruit should also be inspected for evidence of larval feeding.
For more information on the identification, monitoring and management of spotting wing Drosophila, or if you suspect you have spotting wing Drosophila, please contact Cornell Cooperative Extension of Chautauqua County at 664-9502, ext. 202, 204 or 224 or go online to: www.fruit.cornell.edu/berry/pestalerts/drosophilapestalert.html.
Remington Whitcomb contributed to this story.