Laurence Charlet, Robert Aiken, Gerald Seiler, Janet Knodel, Kathleen Grady, Anitha Chirumamilla and Brent Hulke
Abstract: The major insect pests attacking cultivated sunflower include the sunflower stem weevil, the sunflower moth, the red sunflower seed weevil, the banded sunflower moth, and the sunflower midge. Strategies to reduce crop losses for these pests have focused on insecticidal control, but host-plant resistance may provide a sustainable integrated pest management approach for crop protection with lower input costs for the producer and with less environmental impact. Plant resistance is a pest management tactic that utilizes the plant’s own defenses to reduce damage caused by insect pests. Evaluation of sunflower germplasm for resistance to important sunflower seed-feeding and stem-infesting pests has been conducted in regions where these insects have caused economic losses. Nurseries for the banded sunflower moth were located in ND, for the sunflower moth and sunflower stem weevil in KS, and nurseries for the red sunflower seed weevil were located in SD. Results from 2007 identified lines screened against the five insects studied with greatly reduced damage levels among the germplasm tested. There was a difference in seed damage of 90% between the most susceptible and the most resistant line in the sunflower moth, red sunflower seed weevil, and banded sunflower moth trials and 90% fewer larvae per stalk in the stem weevil trials. There were also lines which revealed lower incidence of longhorned beetle attack. After each year of testing lines with low damage are retested to confirm their resistance to attack. Evaluation of selected hybrids for resistance to the sunflower midge was conducted in 2008 in ND. Results showed that commercially available sunflower hybrids vary in their midge reaction. With proper testing, hybrid reaction to midge infestation can be categorized based on a variety of scales which can identify differences even when sunflower midge populations are low. Results from these evaluation trials enable producers to make informed decisions when choosing hybrids to grow in locations where a midge infestation has historically been a problem.
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