Introgression of resistance to cabbage seedpod weevil to canola from yellow mustard

The cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), is an insect pest of major economic importance in the production of canola (Brassica napus L. and B. rapa L.) in Europe and North America. Studies were conducted to test intergeneric germplasm, produced by crossing Sinapis alba L. (yellow mustard) x B. napes and then backcrossing progeny to the B. napus parent, as potential sources of resistance to the weevil. Of 230 intergeneric genotypes evaluated in field trials in 2001,18 had an average of fewer than 0.05 weevil exit holes per pod, a level of resistance selected as conferring appropriate resistance and used for further testing. Subsequent tests confirmed several genotypes that evidently carried genes for resistance to C. obstrictus from the S. alba parent. In field assessments, mean exit holes per pod in the common commercial variety, B. napus cv. Q2, ranged from approximately 2.5 to 8.3 times more than those observed in the resistant lines. Some genotypes appeared to exhibit both antixenotic and antibiotic resistance to C. obstrictus, as indicated by fewer eggs laid per pod and larval development that was significantly lengthened in the resistant germplasm compared with the B. napus check. Introgression produced several genotypes with resistance to cabbage seedpod weevil that can now be crossed with agronomically superior B. napus germplasm; when the weevil-resistant canola is available to producers it can comprise an important component in the integrated management of this pest, resulting in substantial reductions in insecticide use in this crop.