Oviposition Preferences of Bertha ArmywormMamestra configurataWalker (Lepidoptera: Noctuidae) on Different Crucifer Cultivars and Growth Stages

Abstract

Bertha armyworm, Mamestra configurata Walker, oviposition preferences were examined using choice and no-choice experiments with intact cruciferous plants. Previous larval feeding experiments had indicated that some Brassica juncea L., Sinapis alba L., and B. carinata L. lines were relatively resistant to bertha armyworm feeding. To examine oviposition preferences, a representative cultivar from each species was compared with the Brassica napus L. cultivar AC Excel using plants at the full-flower stage in a choice experiment. The S. alba cultivar AC Pennant received the greatest number of eggs, despite being relatively resistant to larval feeding and offering the least amount of foliage among the plants tested. AC Excel was also compared with the B. juncea cultivar AC Vulcan in dual-choice and no-choice experiments. Bertha armyworm oviposition was substantially greater on AC Excel than on AC Vulcan in all experiments. The effects of crop phenology on oviposition were examined using three growth stages (preflower, full-flower, and pod) of B. napus AC Excel in choice tests. The number of egg masses and total number of eggs on each plant were used to measure oviposition. The full-flower plants were significantly more preferred for oviposition than plants in preflower or pod stages. Bertha armyworm laid most eggs in the upper portion of the crop canopy on the underside of leaves.