Abstract: To assess the potential of Mikania micrantha on IPM and provide reference for Brontispa longissima management, the bioactivities and field control effect of extracts of M. micrantha on the coconut leaf beetles were investigated. The results indicated that the extraction rates of methyl alcohol, ethyl acetate, hexane, petroleum ether, chloroform, distilled water and ethanol were 10.54%, 7.17%, 6.22%, 6.28%, 8.67%, 8.62%, 10.36%, respectively. Methyl alcohol and ethanol showed the highest extraction ability among different solvents. The methyl alcohol and ethanol extracts of M. micrantha showed activities to the coconut leaf beetles, and the activity of the ethanol extract was better than that of the methyl alcohol extract. The LC₅₀ of the ethanol extract to 1st to 5th larvae and adults of coconut leaf beetles were 7.09, 7.88, 8.93, 11.88, 13.26 and 17.46 mg/g, while the LC₅₀ values of the methyl alcohol extract were 12.36, 14.85, 15.89, 17.46, 19.91 and 27.81 mg/g, respectively. Both extracts delayed the eclosion of the coconut leaf beetles and induced the deformity of adults. Meanwhile, the time of egg incubation was also delayed, and the bioactivity of the ethanol extract was obviously higher than that of the methyl alcohol extract. The field trial results indicated that the ethanol extract of M. micrantha had great activities to the coconut leaf beetles and the control effects were all above 80% in the 100 mg/mL and 20 mg/mL treatment after 7 d. It is so concluded that the extracts of M. micrantha have good bioactivity and control potential on the coconut leaf beetles.

Key words: Brontispa longissima, Mikania micrantha, crude extract, extraction rate, bioactivity