Efficacy of red sunflower seed weevil resistance from inbred line cms HA 488 in single‐cross hybrids

Abstract

Sunflower line HA 488 (where HA is Helianthus annuus) is resistant to the red sunflower seed weevil, Smicronyx fulvus LeConte, with ≈80% less seed damage compared to susceptible lines. To determine the value of resistance in single‐cross hybrids, six hybrids were created by pollinating weevil‐resistant (cms HA 488, where cms cytoplasmic male sterile) or susceptible (cms HA 412HO) inbred lines with three putatively susceptible restorer lines (RHA 274, RHA 464, or RHA 468) and artificially infesting each with 30 weevils head−1. In 2021–2022, resistant hybrids from cms HA 488 reduced seed damage by ≈40%–50% for hybrids with RHA 274 or RHA 464. However, cms HA 488 did not reduce damage when crossed with RHA 468. Infestation of male‐fertile isogenic lines HA 488 and HA 412HO with 60 weevils head−1 showed resistance remained effective at 12–20 times economic thresholds. Results confirm the value of resistance to S. fulvus for sunflower hybrids but also suggest a need to further examine the role of the male heterotic group in resistance to the red sunflower seed weevil.