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 againstThrips flavusSchrank (Thysanoptera: Thripidae) under laboratory conditions. The plant essential oils were citrus oil (Citrus reticulataBlanco), Chuan-shan pepper oil (Zanthoxylum piasezkiiMaxim.), zanthoxylum oil (Zanthoxylum bungeanumMaxim.), pomelo peel oil (Citrus maxima(Burm.) Merr.) and orange leaf oil (Citrus sinensis(L.) Osbeck). Among the essential oils evaluated, orange leaf oil (LC50= 0.26 g/L), zanthoxylum oil (LC50= 0.27 g/L), and pomelo peel oil (LC50= 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 againstT. flavusafter 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, adultT. flavuswere attracted by zanthoxylum oil and Chuan-shan pepper oil. We speculated that linalool might be the key signaling compound that attractsT. 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 againstT. flavus.Keywords:essential oil;Thrips flavus;insecticidal activity;gastric toxicity;thrips