Resistance of kale varieties to attack by Mamestra brassicae
1 The objectives of this work were to study the resistance of six kale (Brassica oleracea acephala group) varieties to cabbage moth Mamestra brassicae (L.) expressed as antibiosis and to determine the effect of plant age on larval survival and development.
2 The influence of plant age on resistance was determined using leaves from seedlings and from mature plants. Survival and development of M. brassicae larvae and feeding rates were determined in laboratory bioassays.
3 Leaves from seedlings were more suitable than those of mature plants for establishing differences in resistance. There were significant differences between kale varieties in larval survival, growth rate, leaf feeding, and time to pupation but not pupal weight. The varieties MBG-BRS0031, MBG-BRS0351, and MBG-BRS0287 reduced survival of M. brassicae larvae. Larvae that fed on MBG-BRS0060 were the heaviest and took the longest time to pupation. MBG-BRS0031 was consumed significantly less by larvae than were all the other varieties examined. Leaves from mature plants of MBG-BRS0142 and MBG-BRS0170 were defoliated significantly less than those of other varieties.
4 In conclusion, the variety MBG-BRS0031 may be a promising source of resistance to M. brassicae. Leaf antibiotic resistance was shown to play a role in defense against M. brassicae attack but it is not the only possible mechanism of resistance.