Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2016
Publication Date: 12/1/2016
Citation: Prasifka, J.R., Hulke, B.S. 2016. Relative susceptibility of sunflower maintainer lines and resistance sources to natural infestations of the banded sunflower moth (Lepidoptera: Tortricidae). The Canadian Entomologist. 148:736-741.
Interpretive Summary: The banded sunflower moth is a pest of cultivated sunflowers whose larvae feed on florets and seeds. Wild sunflowers and some open-pollinated varieties appear to have some resistance to banded sunflower moth, but no published research has tested the susceptibility of modern inbred lines used to produce sunflower hybrids. Three years of field trials were used to compare released inbred lines (called ‘maintainer’ or HA lines) to resistance sources and unreleased, partially inbred (F6) lines (made by crosses of maintainer lines with resistance sources). Though the released HA lines were more damaged than lines from the other groups, the best inbred, HA 207, had fewer damaged seed than almost all of the resistance sources and unreleased lines. Because released inbred lines often have many other positive traits that known resistance sources lack (high seed oil, high oleic acid content, and disease resistance), breeding with HA 207 or maintainer lines with similarly low banded moth damage may be more practical than working with other resistance sources. However, because it is not clear whether damage to inbred parents accurately predicts damage to hybrids, additional research needs to be done to help progress breeding for banded sunflower moth resistance.
Technical Abstract: The banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera: Tortricidae), is a significant seed-feeding pest of sunflowers in North America. Though some wild Helianthus spp., interspecific crosses, and H. annuus cultivars (that precede hybrid sunflower breeding) have low susceptibility to banded sunflower moth, no apparent effort has been made to evaluate modern inbred lines as a source of resistance for hybrids. In field trials from 2013–2015, inbred maintainer (HA) lines, resistant accessions (PI), and unreleased, partially inbred (F6) lines were evaluated in field trials using natural infestations of banded sunflower moth. Results show greater seed damage to maintainer lines than the other groups, but also significant variability among lines within groups. The best maintainer, HA 207, had ˜ 75% fewer damaged seed than the most susceptible HA lines. Among the resistant PI and unreleased inbred lines, only one entry had significantly less damage than HA 207. While PI 494859 showed banded moth resistance superior to the best inbred lines, its other agronomic liabilities make breeding with the least susceptible maintainer lines appear more practical. A key unknown for any attempts to breed hybrids resistant to banded sunflower moth is how closely damage is correlated between inbred lines and their hybrids.