Efficacy of aerial application of Bacillus thuringiensis to control Spodoptera littoralis (Lepidoptera, Noctuidae) infesting soybean cultivations in Egypt

The calculated percentage of droplets deposition of Bacillus thuringiensis var. kurstaki HD-1 Dipel 2X on the foliage of soybean plants in relation to the sensitive "Ciba Geigy" papers showed to be the highest (92.4%) after g round spray application, compared to an average of 67.4, 85.8 and 89.3% fol lowing aerial application of the same preparation in spray volumes of 10, 2 0 and 30 l/F, respectively. Aerial application of B, t. showed to be more e ffective during the first 3 days after spraying soybean cultivations and th e mortality of Spodoptera littoralis larvae varied between 36.9-67.2% in co rrelation to the spray volume. The volume achieving the highest and signifi cant suppression of infestation was 20 l/F. On the other hand, the yield of soybeans obtained from plots receiving a spray volume of 30 l/F was higher compared to plots sprayed with a volume of 20 or 10 l/F, but with no signi ficant difference when compared to those plots receiving ground spray appli cation.