Belowground battles: root fly resistance in Brassicas

The cabbage root fly, Delia radicum L., is a major threat to Brassica crops. In this study, the presence of antibiosis resistance against D. radicum larvae was evaluated in wild Brassica species and high levels of resistance were identified in B. fruticulosa. The genetic basis of the resistance to D. radicum in a B. fruticulosa F2 population was analysed. One highly significant quantitative trait locus (QTL) was detected. The two accessions that were genotyped for homozygosity of a QTL region were further investigated for possible metabolomic differences. Twenty-five secondary metabolites among which one glucosinolate were linked to constitutive resistance, while six secondary metabolites among which three glucosinolates were linked to induced resistance. Additionally, larval behaviour in the root system and larval development were studied. Breeding for root fly resistance in cabbages and other Brassica crops can be utilised as a component in integrated pest management.