Repellent and insecticidal activity of Gardenia jasminoides essential oil against Zeugodacus cucurbitae adults

The melon fly, Zeugodacus cucurbitae Coquillett, is a significant agricultural pest that damages a variety of fruits and vegetables. Because of its hidden oviposition and and the fruit-boring damage caused by larvae, it is extremely difficult to control. To screen plant essential oils (EOs) with repellent and insecticidal activity against adult Z. cucurbitae, this study evaluated the behavioral repellency and toxicity of 11 aromatic plant EOs, aiming to establish a theoretical foundation for eco-friendly and efficient management of this pest. First, the behavioral repellency of different EOs against Z. cucurbitae was assessed using a Y-tube olfactometer choice assay. Subsequently, the oviposition deterrent activity was tested by fruit spray method. Finally, contact and oral toxicity of the highest repellent activity EO were determined through the drug film contact method and stomach poison method, respectively. The results showed that among the 11 tested EOs, Gardenia jasminoides Ellis EO exhibited the strongest behavioral and oviposition deterrent effects, achieving an oviposition repellency rate of (94.69 ± 2.36)% at 200 µL/mL. At 35 mg/mL, G. jasminoides EO caused (92.00 ± 4.36)% contact mortality in adults, with LC₅₀ values of 15.289 mg/mL (females) and 10.705 mg/mL (males). Additionally, the oral toxicity mortality rate was (94.00 ± 2.46)%, with LC₅₀ values of 16.169 mg/mL (females) and 6.901 mg/mL (males). This study reveals that G. jasminoides EO possesses significant repellent and insecticidal activity against adult Z. cucurbitae, providing a theoretical basis developing eco-friendly behavioral regulators and toxic agents for Z.cucurbitae.