Efficacy of Tithonia diversifolia Leaf Extract Combined with Beauveria bassiana in Increasing Mortality and Reducing the Damage Intensity of Spodoptera exigua on Shallots

Abstract

Red onion (Allium cepa var. aggregatum) is one of the high value horticultural commodities in Indonesia and widely used in traditional cuisine. However, annual growth in production is limited by adverse climatic conditions, diseases, pest attacks and inconsistent cultivation practices. The red onion caterpillar (Spodoptera exigua Hübner) is a significant insect pest that causes heavy losses in yield and quality. The combined effects of Mexican sunflower (Tithonia diversifolia) leaf extract and the entomopathogenic fungus B. bassiana on S. exigua are not well known, although interest in the use of botanical and biological control methods has increased recently. The present study was conducted to assess the efficacy of this natural mixture formulation as a sustainable pest control method. This experiment was conducted at West Java Provincial Horticultural Seed Center using Randomized Block Design (RBD) with seven treatments and four replications. Treatments were a control () and six concentrations of T. diversifolia extract (10, 30, 50, 70, 90 and 110 mL/L) with constant concentration of B. bassiana (14 g/L). The highest concentration (110 mL/L) showed the best performance, with larval mortality rate of 82.49% and reduction in damage intensity of 57.46%. The results indicate that this combined botanical and microbial formulation has the potential to be an environmentally friendly insecticide for sustainable management of red onion pests in Indonesia.