As natural phytocide: Biomarker assessment of Litsea cubeba (Lour.) Persoon essential oil against Drosophila suzukii Matsumura (Diptera: Drosophilidae.)

The essential oil of Litsea cubeba (Lour.) Pers. (LCEO) has applications as a health and food additive. The study objectives were to demonstrate the toxicity of LCEO against Drosophila and to investigate the essential oil's mechanism of action. The repellency percentage, fumigation effect and contact activity were all positively correlated with the LCEO concentration, and 1.0 mu L/cm(2) essential oil repelled Drosophila for 10 min and reached the highest repellant level. Damage to Drosophila organ tissues was assessed by light microscopy, using histological sections to further analyze the mechanism of lethality and treated larvae underwent ultrastructural evaluations. A 6.7-fold decrease in acetylcholinesterase and a 2.7-fold increase in superoxide dismutase indicated significant enzymatic changes, and the two main essential oil action mechanisms on Drosophila were identified, namely neurotoxicity in larvae owing to altered enzyme activities and death owing to homeostatic disruptions by aldehyde oxidation reactions. The phytochemistry of LCEO has broad applications in fruit pest control.