Effect of several types of insecticide on predator population and damage intensity due to soybean pest attack in South Sulawesi, Indonesia

Spodoptera litura was one of the pests that caused soybean seed yield decrease in South Sulawesi. In order to challenge the pests, farmers still largely choose chemical insecticides. This research aimed to establish effectiveness level of several insecticide types that were frequently used by farmers. The design used was Randomized Block Design with 7 treatments (6 insecticide types and 1 control) with 3 replications. The insecticide types examined were: 1) acephate 75%, 2) thiamethoxam 200 g/L + chlorantraniliprole 100 g/L, 3) permethrin 200 g/L, 4) chlorpyrifos 550 g/L + cypermethrin 60 g/L, 5) deltamethrin 50 g/L, 6) profenofos 500 g/L, and 7) polyculture, soybean + corn (control). The result showed that insecticide type of thiamethoxam 200 g/L + chlorantraniliprole 100 g/L was the most effective insecticide to control S. litura with soybean leaves damage intensity (15.19%) and population of Bemisia tabaci whitefly (5.07 tails plant-1). However, thiamethoxam 200 g/L + chlorantraniliprole 100 g/L mostly killed Lycosa sp. predator (0.63 tails plant-1) and Crocothemis servillia (3.26 tails plant-1). The highest predator population was found in multiple cropping of soybean and corn, C. servillia (3.94 tails plant-1), and Lycosa sp. (3.26 tails plant-1). The insecticide of chlorpyrifos 550 g/L + cypermethrin 60 g/L were effective to control soybean pod borer pest Etiella zinckenella (2.40%). Furthermore, insecticide of deltamethrin 50 g/L was effective to control Aphis glycines pest (2.05 tails plant-1). Several types of insecticides are effective in controlling S. litura, N. viridula, and B. tabasi pests, but these insecticides are also effective in killing predators. The highest predator population is soybean-corn intercropping. Keywords: Soybean, insecticides, pests, intensity of damage, predators, seed yields.