The efficacy of three bioinsecticides: the microbial Naturalis (Beauveria bassiana), the botanical Pyrethrum FS EC (pyrethrin + sesame oil + soft potassium soap) and NeemAzal T/S (azadirachtin), allowed for application in organic farming in Bulgaria, against larvae and adults of the Colorado potato beetle, Leptinotarsa decemlineata(Say) (Coleoptera: Chrysomelidae) was studied under laboratory conditions. The best results from the tested products showed microbial insecticide Naturalis (Beauveria

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... bassiana). At a concentration of 0.2%, the efficacy reached 78.4% and 68.4% on the 5th day for larvae and adults, respectively, and 100% on the 7th day after the treatment for both larvae and adults. The preparation showed very good action in its low concentration (0.1%) –efficacy was 88.5% and 68.5% on the 7th day after the treatment for larvae and adults, respectively. Insecticides based on plant extracts showed very good results. The botanical insecticide Pyrethrum FS EC showed a fast initial action and good effectiveness. At a concentration of 0.1%, the efficacy reached 96.5% and 86.5% on the 5th day for larvae and adults, respectively, and 100% on the 7th day after the treatment for both. The preparation showed good action in its low concentration (0.05%) –efficacy was 84.3% and 68.4% on the 7th day after the treatment for larvae and adults, respectively. The botanical insecticide NeemAzal T/S at a concentration of 0.3% the efficacy was 81.8% and 63.7% for larvae and adults, respectively on the 7th day after the treatment. At its low concentration of 0.1%, the NeemAzal T/S had insufficient effect and efficacy was only was 59.3% and 29.8% on the 7th day after the treatment for larvae and adults, respectively.