Insect Work Also Progresses
Thursday, April 1, 2010
filed under: Insects
The effort to find resistance in sunflower germplasm to stem weevil and seed-infesting insect pests also continues to show progress.
The cooperative project, which has been underway for several years, involves scientists with the USDA-ARS at Fargo, N.D., South Dakota State University and Kansas State University*. Its primary emphasis has been the evaluation of a broad range of sunflower germplasm (accessions, interspecific crosses, breeding lines) to see what materials may exhibit reduced larval density of stem weevil and/or lower seed damage from the red seed weevil, banded sunflower moth and sunflower (head) moth.
Since rearing populations of these insects is not a feasible study route, the approach has been to conduct the testing at locations where high populations of the insects occur on a consistent basis. Specifically, that means Prosper, N.D., for the banded moth; Highmore, S.D., for the red seed weevil; and Colby, Kan., for the sunflower moth and stem weevil.
Results to date have shown significant differences in levels of resistance to one or more of these insects across the tested germplasm. While 2009 data were not available as of this writing, 2008 results provide some good examples.
In the ’08 stem weevil trial at Colby, for instance, the range of infestation among the 37 “S1” lines (initial selections from a diverse populations) evaluated was from 13 larvae per stalk up to 57, with 12 ranking below 25 larvae per stalk. Among 52 evaluated F2 (initial inbred) lines, the range ran from 10 up to 51 larvae per stalk, with 19 being below 25 larvae/stalk.
The 2008 sunflower moth trial at Colby evaluated 28 S1 lines, with a very broad range of results: from just 1% all the way up to 84% seed damage, and with 10 at or below 10% seed damage. With 46 F2 and F3 lines, the range was from 1% to 53% seed damage, with 25 being at or below 10%.
The ’08 banded moth tests of 32 S1 lines showed a range of 44 to 90% seed damage — this under extreme banded moth population pressure at Prosper that year. The 50 F2 and F3 lines ranged from 16 to 83% seed damage.
Finally, in the red seed weevil trials at Highmore in 2008, the 36 evaluated S1 lines ranged from zero up to 31% seed damage. Sixteen were below 10%. The 47 F2 lines ranged in seed damage from 2% up to 27%, with 25 being below 10% seed damage.
Yield trials for the sunflower moth and stem weevil germplasm begin in 2010 at Colby. Yield evaluations of red seed weevil and banded sunflower moth materials have already been going on, and they will be continued this season as well.
Key participants have included Larry Charlet (research entomologist), Brent Hulke (research geneticist), Gerald Seiler (research botanist) and Theresa Gross (research technician), all with the USDA-ARS Sunflower Research Unit at Fargo, N.D.; Jan Knodel and Anitha Chirumamilla, North Dakota State University; Kathy Grady, oilseeds breeder at South Dakota State University, Brookings; and Rob Aiken, crops research scientist with Kansas State University’s Northwest Research-Extension Center at Colby.