Comparison of yield loss on cabbage from Diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) using two insecticides

Damage caused by the Diamondback moth (DBM), Plutella xylostella L. on head cabbage (Brassica oleracea var. capitata) was assessed, by applying. Bacillus thuringiensis (Bt) var. kurstaki and a pyrethroid insecticide, λ-cyhalothrin at different growth stages. Yields were increased by 36.1% and 49.4%, respectively in the first season (November planting) and 85.2% and 91.2% in the second season (April planting), using Bt and λ-cyhalothrin, respectively. These yield losses equate to 12 and 20.7 tons/ha in the first season and 27 and 48.7 tons/ha, respectively in the second season. The pre-heading stage was observed to be the critical period of DBM infestation suggesting the need to protect the crop during this growth stage until threshold data are available for use in DBM management.