Project Number: 3625-21000-053-04
Project Type: Specific Cooperative Agreement

Start Date: Aug 22, 2008
End Date: May 31, 2009

Objective:
The object of this research is to thoroughly evaluate a subset of available oilseed rape accessions within the USDA collections to quantify the occurrence, rate, and prospective use of accessions for developing turnip aphid resistance. Also, related Brassica species could be identified that possess resistance, and through interspecific hybridization be bred to adapted winter oilseed rape varieties. If aphid-resistant canola is available to producers it would comprise an important component in the integrated management of this pest, resulting in substantial reductions in insecticide use for the crop. Turnip aphid (Lipaphis erysimi) is the most significant insect pest of winter canola in the southern Great Plains. Winter canola production has increased from 3,000 to 60,000 acres since 2003, and a large number of fields have been devastated by aphid infestations. Agronomists have often inspected fields during winter and pronounced them aphid-free, only to find large numbers of aphids later in the season, with many plants killed and extremely low yields. Initial observations of canola fields have revealed that three aphids (cabbage, turnip, and green-peach) can be found on canola in high numbers in the region. Turnip aphids appear to have the greatest impact, killing young plants in January and February as plants exit winter dormancy. Small plot studies to date suggest that unmanaged aphid infestations can reduce yields by greater than 50%, likely because they occur for an extended period of time from fall through the spring. Results suggest that the impact of aphid infestations in the Southern Plains may be more severe than in the Pacific Northwest (Brown et al. 1999) and in Georgia (Buntin and Raymer 1994). Preliminary research indicates chemical control reduces aphid numbers and protects crop yield. However, high populations in some areas have resulted in the need to treat fields infested with aphids two or more times in a growing season in order to salvage a moderate seed yield. Chemical seed treatment at planting has proven effective in controlling aphid infestations through January, reducing the number of potential chemical applications for control of turnip aphids to one or two. Genetic control of turnip aphids could further reduce the use of chemicals to prevent damage. To date, little work has been completed on turnip aphid resistance in winter oilseed rape. The high yield potential, developing markets for winter canola, and devastating turnip aphid infestations clearly justify development of resistant cultivars in the southern Great Plains. A portion of the Brassica collection at the NCRPIS (NC7) in Ames, IA was recently screened for green-peach aphid (Myzus persicae) resistance with only partial resistance noted. A number of oilseed Brassica accessions exist with potential for turnip aphid resistance. As of October 2007, there are over 3000 Brassica accessions at NCRPIS. A number of these (515) are available B. napus accessions, of which approximately 300 are potential winter types. It is of great interest to breed qualitative resistance to turnip aphids into adapted and agronomically superior varieties of winter canola.

Approach:
In the greenhouse, 300 winter-type accessions of B. napus will be screened for genetic resistance to turnip aphid through replicated laboratory and greenhouse research evaluations in 2008. The effects of controlled-caged infestations (age identified cohorts) on aphid population dynamics and colonization behavior, plant injury, and seed yields for individual plants will be assessed and described. Data will be collected and summarized. Spring-type B. napus and related Brassica species also may be evaluated. Undergraduate workers or temporary support will support seeding, vernalization, artificial infestation with aphids, maintenance, and will assist with scoring of insect damage and data entry. The experiment will require substantial greenhouse resources and the work will be labor intensive. The personnel working on this project will be under the direct supervision of Dr. Kristopher Giles at Oklahoma State and Michael Stamm at Kansas State, who are also responsible for data analysis and interpretation. Additional resources from other projects will be used to complete the work. Both researchers will offer a portion of their time and the full time assistants for each project will spend time monitoring students who will be undertaking most protocols. Greenhouse space will be allocated for the evaluations. These resources will comprise matching funds for the submitted project.