Optimization of mixed botanical insecticides from <i>Azadirachta indica</i> and <i>Calophyllum soulattri</i> against <i>Spodoptera frugiperda</i> using response surface methodology

Abstract The ratio of ingredients in the mixture of botanical insecticides affects the insecticide activity. This study conducted a single and mixed insecticide test of Azadirachta indica and Callophylum soulattri against Spodoptera frugiperda. Insecticide application used the residue method on leaves with a microsyringe and acetone + methanol solvent (4:1). The test concentration was based on the preliminary tests. Optimization of the ratio between A. indica and C. soulattri was carried out using response surface methods. The test results showed that the LC 50 and LC 95 values of the single insecticides A. indica and C. soulattri were 0.099, 0.420 and 0.537, 3.481%, respectively. The response surface method optimization showed that the ratio between A. indica and C. soulattri resulted in the highest mortality and the lowest feed consumption at 2.0800:1.1657. The LC 50 and LC 95 values of the mixed insecticide were 0.030 and 0.224%, respectively. The mixed insecticide of A. indica and C. soulattri has strong synergy at LC 50 and weak synergy at LC 95 . The mixed insecticides of A. indica and C. soulattri can be used as an alternative environmentally friendly control against S. frugiperda in maize fields.