Insecticidal effects of Tabebuia avellanedae-derived Constituent and its analogues against Nilaparvata lugens and Laodelphax striatellus

Insecticidal activities of an active constituent derived from the bark of Tabebuia avellanedae and its analogues were examined using a micro-topical application bioassay against the brown planthopper, Nilaparvata lugens and the small brown planthopper, Laodelphax striatellus. The active constituent of T. avellanedae bark was characterized by various chromatographic methods and identified as 2-Hydroxy-3-(3-methyl-2-butenyl)-1,4-naphtoquinone. On the basis of 48 h lethal concentration 50 (LD50) values, the most toxic compound against N. lugens was 1,4-Naphtoquinone (0.042 μg/female), followed by 5,8-Dihydroxy-1,4-naphtoquinone (0.080 μg/female), 2-Hydroxy-3-(3-methyl-2-butenyl)-1,4-naphtoquinone (0.091 μg/female), and 2,3-Dichloro-1,4-naphtoquinone (0.186 μg/female). Similar results against L. striatellus were observed for 2-Hydroxy-3-(3-methyl-2-butenyl)-1,4-naphtoquinone and its analogues, except for 2,3-Dichloro-1,4-naphtoquinone and 5,8-Dihydroxy-1,4-naphtoquinone. These results indicate that T. avellanedae bark-derived material and its analogues have potential as new preventive agents for control of N. lugens and L. striatellus.