Wednesday, June 29, 2011

New Pests: Spotted Wing Drosophila and Kudzu Bug

There are two new insect pests that growers need to be aware of, spotted wing drosophila and the kudzu bug.

Spotted wing drosophila (SWD) is an invasive fruit fly pest of soft-skinned fruit (strawberry, blueberry, blackberry, raspberry, etc.). SWD was first observed in California in 2008 and then identified in 2009. In 2010, Dr. Hannah Burrack of NC State began an intensive monitoring plan for SWD in the Southeast. SWD was captured in NC and SC late 2010. SWD gets its name because the males have two spots on the end of their wings (one on each). Female SWD do not have spotted wings, but do have a serrated oviposter. This serrated oviposter allows the female to lay eggs in sound fruit, unlike common fruit flies which prefer decaying fruit. Because of this, SWD has potential to be an economically limiting crop.

SWD trapping is well underway throughout NC, in fact SWD was captured in Henderson County in mid-June. Small fruits producers are encouraged to start a monitoring program. Dr. Burrack explains how to construct and monitor SWD traps and how to identify them.

For treatment considerations, visit Dr. Burrack's post What to watch for: When treating SWD.

To read more about SWD or to view images, please visit Dr. Burrack's SWD page on her NC Small Fruits, Specialty Crops and Tobacco IPM blog.

If you would like assistance with monitoring, please contact me at or your local extension office.

Kudzu bug (adult) on soybean leaf.

Multiple kudzu bugs (adults) on soybean stem.

The next pest is the kudzu bug. This pest prefers legume crops, especially soybeans, but has also been observed feeding on potatoes, cotton and wheat. The kudzu bug was confirmed in central Georgia in 2009 and then spread throughout the state and to neighboring states in 2010. This pest has been identified in many NC counties, including Buncombe and Henderson Counties on soybeans. This pest isn't thought to be a problem on most vegetables, but those who grow edamame soybeans or potatoes should be concerned. The kudzu bug is a stem and leaf feeder, so far there have been no reports of the kudzu bug feeding on blooms or pods.

Based on Georgia data the economic threshold is one bug per sweep with large nymphs present, or three bugs per plant with large nymphs present. This pest is very mobile and will re-invade after treatment, so capturing or observing nymphs is important. According to the latest edition of NC Pest News, killing this pest has been relatively easy with conventional insecticides except the neonicotinoids (kudzu bug seem to be attracted to areas that have been treated with neonicotinoids). For organic producers, PyGanic is recommended. Other options are options are azadirachtin (Azagard) or kaolin clay (Surround), but the efficacy of these products is unknown.

To read more about the pest, see more pictures and a map of kudzu bugs movement in the southeastern US, see the June 24th of NC Pest News.

No comments: