Populations of Aphis gossypii on different pepper cultivars, fertilized with different rates of NPK

Cotton aphid (Glover), (Aphis gossypii) (Hemiptera: Aphididae), is one of the main insect pests of chili plants in Indonesia. Excessive use of insecticide has caused resistance in the pest to insecticides in many places. Besides that, a high dose of fertilizer could trigger a population increase of many aphid species. Therefore, effective and safer alternative aphid control methods must be sought; hence the purpose of this study was to determine the resistance of different chili cultivars against the pest and the optimal dosages of the compound fertilizer of nitrogen, phosphate, and potassium (NPK) to suppress the aphid populations. The study was conducted in the Experimental Farm of the Faculty of Agriculture, Hasanuddin University, Makassar, from March to August 2019. This experiment was arranged in a complete randomized block design in factorial. The first factor was red pepper cultivars: Lado F-1 and Pilar F-1, and the second factor was NPK fertilization rate: 1, 2, 4, 8 g per plant. The results showed that the number of aphids was significantly lower on Lado F-1 than on Pilar F-1. There was a tendency that as the fertilizer rate increased, the number of aphids also increased. Plants fertilized with 8 g NPK per plant had a significantly higher number of aphids compared to the other treatments. However, the numbers of aphids on other treatments were not significantly different from each other. Therefore, the results suggested that in order to suppress the aphid population, farmers should use the Lado F-1 and fertilization rate of 1 to 4 g per plant as important components in an integrated pest management program.