Genetics of apetalous sunflowers and implications on IPM strategies

Annual sunflower (Helianthus annuus L.) is an oilseed crop grown throughout the world. Sunflowers are known for their showy yellow petals, which may be important visual cues both for insect pollinators and pests. In particular, the red sunflower seed weevil (Smicronyx fulvus L., or RSSW), is a severe pest that coevolved with wild sunflowers and may use petals to locate its host. Though potentially breeding sunflowers with reduced numbers of petals (hereafter, apetalous) to reduce RSSW damage is an unusual strategy, extremely high populations and resistance to common pyrethroid insecticides in some areas suggest a combination of several complementary strategies is warranted. Parental lines with varied petal number and disc coloration were crossed to create a population that enables tests of the effects of visual cues on sunflower insects (see G. Hirzel et al. presentation) and the genetic basis for the apetalous trait. Results of plant genetic studies on the apetalous trait (inheritance and penetrance) help inform the feasibility of altering sunflower’s visual appearance as part of an integrated pest management (IPM) approach to managing RSSW.