Writers: Dave Mayes, (979) 845-2803, d-mayes@tamu.edu
Pam Dillard, (806) 359-5401, p-dillard@tamu.edu
Contact: Dr. Mark D. Lazar, (806) 359-5401,: m-lazar@tamu.edu
BUSHLAND – Agricultural scientists here are having some major successes in developing wheat that is resistant to greenbugs, the single most damaging insect pest for small grains in the southern Great Plains.
The release last year of TAM 110, the first U.S. wheat variety resistant to certain types of greenbugs, was the result of a breeding program that successfully utilized a gene that overcomes one of the insect’s most troublesome traits.
Greenbugs can rapidly develop new types, called biotypes, that are capable of overcoming resistant varieties, explained Dr. Mark Lazar, a researcher with the Texas Agricultural Experiment Station who helped conduct the breeding program that led to the development of TAM 110.
The source of these new biotypes is unknown, but their economic impact is huge, he said. The lack of resistant varieties has been estimated to cost the region’s producers $240 million a year in crop losses and pesticide usage.
In the Bushland researchers’ breeding program, Lazar said, “we have developed wheat lines very closely related to each other, but differing for a single resistance gene. This gene confers resistance to three biotypes, E, I and K.”
Wheat in the seedling stage that lacks a resistance gene can be killed in two weeks by an initial population of six insects per plant, he noted.
“Under the same conditions, wheat possessing the resistance gene suffers a slight growth reduction but is otherwise immune.”
In another significant finding, both greenbug reproduction and rate of development are reduced by the resistant wheat.
“Also, when greenbugs are reared continuously on the resistant line, for three successive generations,” Lazar continued, “they do not adapt to the resistance by gradually increasing their reproductive or developmental rates.”
“We have produced a large number of lines possessing resistance that have been transferred to the breeding program for evaluation,” he said. This resulted in the release of TAM 110, which is resistant to biotypes E, I and K greenbugs.
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