Chemical Compositions and Insecticidal Activities of Citrus reticulata Essential Oils Against Lasioderma serricorne...

Lasioderma serricorne is a prevalent stored-product pest that infests various grains and processed foods. The overuse of synthetic insecticides has led to insecticide resistance and environmental contamination. Plant essential oils (EOs) have emerged as a promising eco-friendly alternative. The present research extracted EOs from Citrus reticulata different parts (fruit peel, flower, branch, and leaf) and collected leaf EOs at different extraction times via hydrodistillation. Peel EO was dominated by d‑limonene (98.13%), whereas flower EO contained d‑limonene (30.56%) and 3-carene (22.23%) as major components. In leaf and branch EOs, γ‑terpinene was the primary component (56.63% and 28.09%, respectively). Peel EO exhibited the strongest contact toxicity (LD₅₀ = 8.23 mg/L air). For leaf EOs collected in segments, their contact toxicity increased with extraction time, with EO extracted during the fourth time segment (CRL-4) showing the highest activity (LD₅₀ = 8.65 mg/L air). The third time-segment leaf oil (CRL-3) demonstrated excellent repellent activity and persistence, maintaining a consistently high repellency rate of 96% after both 2 and 4 h of exposure. Overall, our study was the first to report the insecticidal and repellent effects of C. reticulata EO against L. serricorne; these findings demonstrated that C. reticulata EOs can serve as eco-friendly alternatives to synthetic insecticides.