Evaluation of insecticidal activity of the essential oil of Eucalyptus robusta Smith leaves and its constituent compound against overwintering Cacopsylla chinensis (Yang et Li) (Hemiptera: Psyllidae)

Abstract

Water-distilled essential oil from Eucalyptus robusta Smith leaves was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Thirty-six compounds, accounting for 96.21 % of the total oil, were identified and the main components of the essential oil of E. robusta leaves were α-pinene (30.18%), 1,8-cineole (26.08%), and spathulenol (5.31%), followed by globulol (4.44%), and viridiflorol (3.97%). The essential oil of E. robusta leaves possessed contact toxicity against the overwintering adults of Chinese pear psylla (Cacopsylla chinensis) with a LD50 value of 10.61 μg/adult. The two main constituent compounds, α-pinene and 1,8-cineole exhibited strong acute toxicity against the overwintering Chinese pear psylla with LD50 values of 1.34 μg/adult and 11.76 μg/adult, respectively