Hessian Fly Resistant Germplasm Available

WASHINGTON - Feb 11/05 - SNS -- The USDA is making three new spring wheat germplasm lines to plant breeders interested in creating commercial wheat varieties resistant to the Hessian fly.

According to ARS geneticist Steven Xu, who is accepting seed requests, resistance in wheat is critical to stopping the fly, during its maggot stage, from feeding inside the plant, causing stems to buckle or stunting growth.

American farmers have been battling the 1/8-inch-long, mosquitolike fly (Mayetiola destructor) since the Revolutionary War, when German auxiliary troops for the British, called "Hessians," purportedly brought the pest here in straw bedding. Today, M. destructor is a major insect pest of wheat in most states where the crop is grown. Though sporadic, Hessian fly outbreaks are costly, inflicting multimillion-dollar crop losses.

Adding to wheat growers' woes: The fly eventually overcomes the defenses of resistant varieties by evolving into new strains, or biotypes. The new spring wheat lines, dubbed "Synthetic Hexaploid Wheat" 8, 34 and 39, all resist the Hessian fly Great Plains (GP) biotype. SW8 also resists the H13-virulent strain, according to Xu, who is in the ARS Cereal Crops Research Unit, Fargo, N.D.

Xu collaborated with entomologist Marion Harris and geneticist Xiwen Cai of North Dakota State University (NDSU) at Fargo to evaluate the spring wheats' resistance to the fly and to investigate the inheritance of that resistance. The initial cross-breeding work was done in the 1980s by former ARS geneticist Leonard Joppa, notes Xu, who will register the germplasm lines in the journal Crop Science.

The germplasm lines, which ARS and NDSU jointly released, derive their Hessian fly resistance from goatgrass, Aegilops tauschii, a wild wheat species that Joppa crossed with the durum wheat cultivar Langdon.

Resistant varieties alone aren't enough to completely stop the fly. Wheat farmers also use delayed planting dates, biological control, crop rotation and other strategies, according to Xu.