Cabbage seedpod weevil resistance in canola (Brassica napus L.), yellow mustard (Sinapis alba L.) and canola x yellow mustard hybrids

Canola, yellow mustard and yellow mustard x canola hybrids were screened for resistance to Ceutorhynchus obstrictus (Marsham) in a series of greenhouse and laboratory choice tests. Tests were conducted using small and large cages designed to hold Brassica pods or whole plants, respectively, with ovipositing female C. obstrictus. Pods were examined for feeding punctures, eggs laid and exit holes that resulted from emerging larvae. All yellow mustard cultivars examined were highly resistant to C. obstrictus feeding and egg laying. In addition, hybrid lines were found with significantly reduced feeding punctures, oviposition, and exit holes compared with canola. A negative relationship was observed between total glucosinolate content of seed and C. obstrictus resistance; however, in both detached pod and whole plant choice tests, hybrids were identified with high seed glucosinolate content that were more susceptible than the most susceptible canola. The relatively poor association between total seed meal glucosinolate content and C. obstrictus resistance is highly important and plant breeders should be able to develop canola-quality oil and seed meal characteristics with improved C. obstrictus resistance using yellow mustard x canola hybrids. The effect of specific glucosinolate types on C. obstrictus resistance may be more complex than previously thought, and further research will be needed to better understand the relationship between specific glucosinolate types and resistance to C. obstrictus.