Two bioinsecticides based on Bacillus thuringiensis sub species kurstaki (Btk) and aizawai (Bta) and non-systemic insecticide of biological origin based on spinosad were evaluated on cauliflower crop for diamondback moth, Plutella xylostella (L.) (Lep.:Plutellidae) control. The experiment was conducted in a vegetable production area of Brazlândia, Brazil. The crop was conducted using the same technology of production adopted by farmers for pest control management. The experiment was conducted between July and September 2002. Randomized blocks with four treatments and four replications were used. Six holes per plant in the four central leaves, were used as a parameter to indicate the necessity of applying insecticides. The number of holes was evaluated weekly. Based on this parameter spinosad was applied three times and Btk and Bta six times. Similar results were obtained in the treatments using insecticides. However significant differences in production were observed between treatments in which insecticide was used and the untreated control. The area treated with Btk produced 78.1% of commercial heads, the area treated with Bta 76.5 % and the one treated with spinosad 75.5 %. On the untreated area 34.4% of the production was lost. The increase on profitability per hectare were U$ 785.32; for Btk U$ 592.99 for spinosal and U$ 612.71 for Bta.
Bacillus thuringiensis; biological control; bioinsecticides; spinosad