Cochylis hospes (Lepidoptera: Tortricidae) damage to male lines varies significantly and inbred susceptibility predicts damage to hybrids

Abstract

Larvae of Cochylis hospes (Walsingham) (Lepidoptera: Tortricidae) (banded sunflower moth) are a primary source of insect damage to seeds of cultivated sunflower, Helianthus annuus Linnaeus (Asteraceae), in North America. Field trials were used to evaluate seed damage under natural infestations for panels of publicly released male lines, publicly derived hybrids (females crossed to one common male parent), and commercial hybrids over a total of four years. For trials in 2013–2014 including 17 male lines, seed damage ranged from 3% to 19%. The least damaged male, RHA 266, was statistically similar to one other male, RHA 455. Three commercial hybrids used as checks also received very little seed damage (< 5%). In trials during 2016–2017, hybrids created by pollinating 15 different female lines with RHA 266 showed 4–14% damage. Data from female parents explained about 28% of variation in seed damage for the hybrids. Results confirm cultivated sunflower has greater variation in susceptibility to C. hospes than previously believed, and that seed damage to inbred lines provides some predictive power for hybrids. Though breeding for resistance to C. hospes seems possible, it may be too labour-intensive without relating resistance to more easily measurable traits or genetic markers.