Another Invasive Pest Discovered in Pennsylvania

12/1/2012 7:00 AM

UNIVERSITY PARK, Pa. — Penn State researchers recently discovered the African fig fly in Pennsylvania for the first time, giving fruit growers across the state another invasive pest to be on the look out for.

Zaprionus indianus Gupta, commonly known in Brazil as the African fig fly, was discovered last month by the Pennsylvania Department of Agriculture in grape and pest survey traps.

David Biddinger, biocontrol specialist at the Penn State Fruit Research and Extension Center in Biglerville, also positively identified the invasive fly in apple cider vinegar traps used for the seasonal monitoring of spotted wing drosophila, another recently introduced invasive pest of small-fruit crops that Biddinger first detected in Pennsylvania and Maryland in July.

After reviewing samples from 2011, Biddinger discovered that the African fig fly has been in Adams county for the past two growing seasons.

“This is important because AFF is considered a tropical pest. Not only did it survive the extremely mild winter of 2011-12, but also the more typical previous winter,” Biddinger said.

He points out that while SWD traps have greatly increased in the past two weeks despite heavy frosts, the same vinegar traps are no longer catching AFF, which is now recorded from Adams, York, Dauphin and Clearfield counties, according to the Pennsylvania Department of Agriculture.

According to Biddinger, AFF is easily distinguished from all other fruit flies in our region due to a pair of silvery-white strips from antennae to thorax tip that are outlined along both sides by black stripes.

“The (Pennsylvania Department of Agriculture) has humorously nicknamed AFF the speed racer fly’ since it has prominent racing stripes’,” he said.

Adults of this species are slightly larger in size than the spotted wing drosophila, and the background color of the body is lighter than most other drosophilid flies commonly found in vinegar monitoring traps.

Native to Africa, the Middle East and Eurasia, the fly is now found in much of South and Central America where it is mainly a pest of figs. It was first found in Florida in 2005, where it quickly spread and out-competed other fruit flies.

New records were found for Michigan, North Carolina, and Connecticut in September of this year, and it appears to be spreading throughout the South as far west as Texas.

Since it does not have a large, sharp ovipositor like SWD females, AFF appears to attack only damaged and overripe fruit, and the harsher winters of Pennsylvania may prevent it from establishing as aggressively here as it did in Florida.

“So far, numbers of adults collected in vinegar traps have been only a fraction the number of SWD collected,” Biddinger said. “An exception is from net collected samples in a grape vineyard where numbers of AFF greatly outnumbered SWD. While it appears from our samples that grape is not a preferred host of SWD, it may be that grape is preferred by this new fruit fly. AFF also has the potential to damage small fruits such as cherries, blueberries, blackberries, strawberries and raspberries.”

The fly’s presence and damage potential in grapes and other crops is under investigation by Biddinger’s lab and Kathy Demchak, Penn State small fruit specialist. Monitoring efforts throughout the state will continue next season by the state Department of Agriculture and Penn State, and records for new hosts and county records can be forwarded to either institution.

For more information about the new fly and other fruit pests, visit Penn State’s Fruit Research and Extension Center website at http://agsci.psu.edu/frec.

The Pennsylvania IPM program is a collaboration between the Pennsylvania State University and the Pennsylvania Department of Agriculture aimed at promoting integrated pest management in both agricultural and urban settings.

For more information about the Pennsylvania integrated pest management program, call 814-865-2839 or visit www.paipm.org.


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