The Efficiency of Viral and Bacterial Entomopathogens Formulated with Chitinase for Biocontrol of Lepidopteran Cabbage Pests

Preparations of Bacillus thuringiensis subspecies galleriae (Bt), Mamestra brassicae nucleopolyhedrovirus (MbNPV) and chitinase were used in laboratory and field experiments to investigate the efficiency of this triple composition against Lepidopteran cabbage pests. Bt subspecies galleriae was shown to be the most relevant among three Bt subspecies against the cabbage moth Mamestra brassicae L. (Lepidoptera: Noctuidae), the diamondback moth, Plutella xyllostella L. (Lepidoptera: Plutellidae) and the large white butterfly, Pieris brassicae L. (Lepidoptera: Pierilidae). Synergistic toxic effect against pests mentioned above was obtained when the Bt and chitinase were used together. M. brassicae larvae on cabbage were much less susceptible to Bt than other pests. It was necessary to include MbNPV in the mixture. Analysis of the different mixtures allowed us to develop the optimal one containing 2.5 ‐ 10 7 spores ml m 1 of Bt , 1 ‐ 10 7 polyhedra ml m 1 of MbNPV and 0.5 mU ml m 1 of chitinase. Such triple com...