Diversity of Predatory Insects on Edamame Soybean (Glycine max (L.) Merrill) Applied with Mexican Sunflower (Tithonia diversifolia) Leaf Insecticide

Abstract

Edamame soybean (Glycine max (L.) Merrill) is a high-value agricultural commodity with great potential for development in highland areas such as Sembalun, East Lombok, but its cultivation is constrained by pest attacks such as armyworms, aphids, and thrips which can significantly reduce yields. Chemical pesticides are commonly used, but they negatively affect the environment, non-target organisms, and natural enemies such as predatory insects. Botanical insecticides like Tithonia diversifolia leaf extract, which contains bioactive compounds such as flavonoids, alkaloids, and saponins, have been developed as environmentally friendly alternatives, although their effects on predators remain less studied. This research aimed to analyze the diversity of predatory insects on edamame soybean treated with various concentrations of T. diversifolia extract. The study was conducted from May to July 2024 in Sembalun using a Randomized Block Design with six treatments (P0 = 0%, P1 = 3%, P2 = 4%, P3 = 5%, P4 = 6%, P5 = 7%) and four replications, totaling 24 plots. Insect collection was carried out using pitfall traps, yellow pan traps, yellow sticky traps, and direct observation, followed by diversity index analysis. Results showed a total of 504 predatory insects recorded over 8 weeks, with the highest abundance at P0 (123 individuals) and the lowest at P5 (38 individuals), dominated by the genera Oecophylla, Philonthus, and Paederus. The highest diversity index (H’ = 2.38, moderate) and evenness index (E = 0.99, high) were observed at P0, while the highest dominance index (D = 0.10, low) was found at P3 and P4. These findings indicate that T. diversifolia extract reduces predator abundance but maintains ecological balance at moderate levels, supporting its potential role in sustainable pest management.