Preliminary Study on Insecticidal Potential and Chemical Composition of Five Rutaceae Essential Oils against Thrips flavus (Thysanoptera: Thripidae).

To meet the demand for novel pest management strategies to combat the development of insecticide resistance, plant essential oils may be a promising alternative source. This study investigated the insecticidal activity of five essential oils from the Rutaceae plant family against Thrips flavus Schrank (Thysanoptera: Thripidae) under laboratory conditions. The plant essential oils were citrus oil ( Citrus reticulata Blanco), Chuan-shan pepper oil ( Zanthoxylum piasezkii Maxim.), zanthoxylum oil ( Zanthoxylum bungeanum Maxim.), pomelo peel oil ( Citrus maxima (Burm.) Merr.) and orange leaf oil ( Citrus sinensis (L.) Osbeck). Among the essential oils evaluated, orange leaf oil (LC 50 = 0.26 g/L), zanthoxylum oil (LC 50 = 0.27 g/L), and pomelo peel oil (LC 50 = 0.44 g/L) resulted in a higher gastric toxicity under laboratory conditions. The results of the pot experiment also showed that orange leaf oil (93.06 ± 3.67% at 540.00 g a.i.·hm -2 , 97.22 ± 1.39% at 720 g a.i.·hm -2 , 100.00% at 900.00 g a.i.·hm -2 ) zanthoxylum oil (98.73 ± 1.27% at 900 g a.i.·hm -2 ), and pomelo peel oil (100.00% at 900 g a.i.·hm -2 ) exhibited a higher control efficacy, being the most effective against T. flavus after 7 days of treatment. The essential oil components were then identified by gas chromatography-mass spectrometry (GC-MS). The insecticidal activity of orange leaf oil, pomelo peel oil, and zanthoxylum oil could be attributed to their main constituents, such as methyl jasmonate (50.92%), D-limonene (76.96%), and linalool (52.32%), respectively. In the olfactory test, adult T. flavus were attracted by zanthoxylum oil and Chuan-shan pepper oil. We speculated that linalool might be the key signaling compound that attracts T. flavus . These results showed that orange leaf oil, zanthoxylum oil, and pomelo peel oil exhibited insecticidal activities under controlled conditions. They can be implemented as effective and low-toxicity botanical insecticides and synergistic agents against T. flavus .