Biological Efficacy of Alcoholic Leaf Extract of Calotropis gigantea against Aphis gossypii on Chili Pepper

Abstract

Aims: This study evaluated the alcoholic leaf extract of Calotropis gigantea for its effects on Aphis gossypii infestation, chili yield, and natural enemy arthropod diversity under field conditions. Study Design:  This study was an experimental investigation conducted in the laboratory using a completely randomized design (CRD) and in the field using a randomized complete block design (RCBD). Place and Duration of Study: The study was conducted at the Plant Pest Science Laboratory, Faculty of Agriculture, and the Chemistry Laboratory, Faculty of Mathematics and Natural Sciences, Tadulako University, as well as in the field at Lolu, Sigi Biromaru District, Sigi Regency. The research was carried out from May to October 2025 Methodology: This study was an experimental investigation conducted under laboratory conditions. Alcohol-macerated leaves of C. gigantea collected from the Palu Valley were evaluated through laboratory assays at concentrations of 1.0, 0.5, 0.25 mg L⁻¹ and control, and field trials at 40, 30, 20, 10, and 5 mg L⁻¹, including positive and negative controls. Applications were initiated at 3 weeks after transplanting and repeated at 7-day intervals for six applications. Observed parameters included aphid population density, infestation intensity, diversity of natural enemies, and chili yield. Results: The leaf extract of C. gigantea exhibited strong toxicity against A gossypii, with an LC₅₀ of 0.513 µg L⁻¹. Field application significantly reduced aphid population density and infestation intensity in a dose-dependent manner. High extract concentrations 40 g/l (K4) achieved suppression levels comparable to synthetic insecticides (K+), while untreated plots showed progressive population increases. Diversity indices of natural enemies were not significantly affected by extract treatments, indicating minimal non-target effects. Crop yield increased significantly with extract application, with the highest dose producing yields equivalent to synthetic insecticide controls. Conclusion: C. gigantea leaf extract effectively controlled. A. gossypii in a dose-dependent manner, with high concentrations achieving suppression comparable to synthetic insecticides. The extract did not negatively impact natural enemy diversity and significantly increased chili yield, highlighting its potential as an environmentally friendly and sustainable alternative for integrated pest management.