UNL CropWatch April 7, 2011 UNL Researchers to Survey for Proof of Wheat Stem Sawflies

UNL CropWatch April 7, 2011 UNL Researchers to Survey for Proof of Wheat Stem Sawflies

 

Wheat stem sawfly adult female


Figure 1. An adult female will deposit a single egg per stem; after hatching, the larva will feed on the stem.

Photo of wheat stem sawfly feeding areas

Figure 2. Darkened areas develop on the stem where the heaviest wheat stem sawfly feeding occurs.

Photo: Stem damage from larval feeding

Figure 3. The most distinct damage is visble at the end of the growing season after larvae cut stems to form pupal chambers, resulting in lodged wheat. (Photos by Gary Hein,Susan Harvey, and Jeff Bradshaw, UNL)
 

April 7, 2011


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Western Nebraska wheat growers are being asked to participate in a survey of wheat stem sawfly being conducted by the Entomology Lab at UNL’s Panhandle REC in Scottsbluff.

University researchers fear the sawfly could be more widespread than previously thought, and pose a major risk to the crop. Grower participation will be key to accurately assessing the situation.

The wheat stem sawfly (WSS) is an important pest in many areas of the northern Great Plains and has been known to infest wheat fields primarily in Scotts Bluff, Banner, and Kimball counties. During the 2010 Wheat Disease Survey conducted by UNL faculty, wheat stem sawfly adults were easily observed throughout the Panhandle in late May and early June. This indicates that this insect may be more prevalent and present a more serious risk than previously thought.

Certain tillage practices may provide a favorable environment for this insect and may be responsible for its expanding range. Figures 1-3 show how wheat stem sawflies develop in and affect wheat plants.

The wheat stem sawfly overwinters as a mature larva in wheat stubble. In May, after pupating, it emerges as an adult.

Adult females deposit a single egg per stem in developing wheat. The hatched larva will begin to feed within the stem. Although blackened areas can develop on the stem (where the heaviest feeding occurred), the damage is most distinct at the end of the growing season after larvae have cut stems to form pupal chambers, resulting in lodged wheat.

In response to this increasing concern, the Entomology Lab at the Panhandle Research and Extension Center will survey growers's fields to document the prevalence and abundance of the wheat stem sawfly and its parasitoids.

With help from crop specialists, extension educators, crop consultants, and agribusinesses, growers throughout western Nebraska will be invited to participate in the survey. Wheat fields will be sampled for insect damage and the presence of parasitoids, which can greatly impact sawfly populations.

This survey should prove interesting and beneficial to wheat producers in western Nebraska. Grower participation will be the key to an accurate and informative survey. Any grower interested in this project should contact:

Susan Harvey, Research Technician, Panhandle REC
Phone: 308-632-1250
Email: sharvey2@unl.edu

Susan Harvey, Research Technician
Jeff Bradshaw, Extension Entomology Specialist
Panhandle REC, Scottsbluff