Effect of Bacillus thuringiensis, Neem, and Karate on Diamondback Moth (Plutella xylostella L.) (Lepidoptera: Plutellidae) Damage on Cabbage in the Central Rift Valley of Ethiopia

The effect of two serotypes of Bacillus thuringiensis (Bt), namely, kurstaki and aizawai, which are referred to as Dipel and Xen Tari by their trade name, respectively, neem seed water extract at the rate of 25 g (Neem 25) and 50 g (Neem 50) per liter of water, neem oil (Nimbecidine) and Karate (λ-cyhalothrin) were tested on diamondback moth (DBM) ( Plutella xylostella ) at two major cabbage growing areas, Melkassa and Wonji for two seasons, October 2005 to January 2006 and March 2006 to July 2006. Dipel, Xen Tari, Neem 25 and Neem 50 were effective in controlling DBM at both locations. As a result, the yield of cabbage improved; for instance at Wonji, marketable yield ranged from 33.4 to 35.1 ton ha-1, for Neem 25, Neem 50, Xen Tari and Dipel treatments; while marketable yield ranged from 19.7 to 22.5 ton ha-1 for Karate and Nimbecidine. This finding indicates that the use of Bt and neem seed extract should be considered in an integrated management strategy for the diamond backmoth. Keywords : Bacillus thuringiensis; Brassica oleracea; Plutella xylostella; Azadirachta indica