Efficacy of aerial application ofBacillus thuringiensis to controlSpodoptera littoralis (Lepidoptera, Noctuidae) infesting soybean cultivations in Egypt

The calculated percentage of droplets deposition ofBacillus 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 ground spray application, compared to an average of 67.4, 85.8 and 89.3% following aerial application of the same preparation in spray volumes of 10, 20 and 30 l/F, respectively. Aerial application ofB. t. showed to be more effective during the first 3 days after spraying soybean cultivations and the mortality ofSpodoptera littoralis larvae varied between 36.9–67.2% in correlation to the spray volume. The volume achieving the highest and significant 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 significant difference when compared to those plots receiving ground spray application.