New Alternative to Control Stenoma impressella (Lepidoptera: Elachistidae) Using Bacillus thuringiensis Commercial Formulations in Oil Palm Crops

Abstract

Using chemical insecticides in IPM is possible and could be sustainable. To find a sustainable alternative to control S. impressella, we assessed the biological activities of five commercial formulations of Bacillus thuringiensis. First, these formulations were evaluated under laboratory conditions. No differences were observed between the commercial formulations Bt_A_1, BT_K_2, and Bt_K_3. Then, the three formulations were compared in further experiments. This bioassay was performed under field conditions in palms naturally infested by S. impressella, and differences in larval mortality rates were observed between commercial formulations. The mortality rates caused by Bt_A_1 and BT_K_3 did not significantly differ. The third step evaluated different doses of Bt_A_1 and BT_K_3 formulations (250, 500, 750, and 1000 g/Ha) under field conditions. Seven days after spraying, differences were only observed between Bt_A_1 and BT_K_3 and the control. Finally, these two formulations were evaluated under field conditions. The mortality rates caused by Bt_A_1 and BT_K_3 were 77.2% and 85.3%, respectively. These findings show that commercial formulations of B. thuringiensis subsp. aizawai (Bt_A_1) and B. thuringiensis var. aizawai (BT_K_3) exhibit high biological activities against S. impressella larvae and can be included in the integrated management of S. impressella.