Suitability of Brassica juncea (Brassicaceae) as a host plant for oviposition for Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae)

The suitability of Brassica juncea (L.) Czern as a host plant for oviposition for Lygus lineolaris (Palisot de Beauvois) was measured by comparing egg laying on five experimental lines or cultivars of this species with that on B. napus L. (cv. AC Excel, a suitable host) in no-choice or choice tests during it 14-d period in the greenhouse and field. Egg laying was measured indirectly by counting newly hatched nymphs emerging from the plants. The numbers of nymphs emerging from B. juncea (cv. Cutlass) and four experimental lines of B. juncea were about two to ten times lower than from B. napus, indicating that L. lineolaris females lay fewer than half as many eggs on the former species than on the latter species and that B. juncea as a species is a poor host plant for oviposition. The inflorescence was the preferred region of the plant for oviposition on B. napus but not on B. juncea. The numbers of nymphs emerging from the inflorescence of B. juncea (cv. Cutlass) were 8.4 times lower than from the inflorescence of B. napus, indicating that the differences in oviposition on these species were due to the presence of an antixenosis-type of plant resistance factor(s) in the inflorescence of B. juncea.