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The brown planthopper, Nilaparvato lugens Stat. (BPH) is the most devastating insect pest in rice fields. Outbreaks of BPH, which are resistant to many synthetic insecticides, can cause total rice crop loss. This research was done to evaluate the efficiency of extracts of mangosteen pericarp (Garcina mangostana L.) as an alternative control of BPH Thailand strain. Topical spraying was applied to various stages of nymphal and adult BPH to determine toxicity. An ethanol extract of mangosteen pericarp extract gave the best control of BPH, with LC50 of 4.5% w/v (r2 = 0.95) with 3rd instar BPH nymphs when compared with the other solvents, hexane, acetone and dichloromethane. The active compound, alpha-mangostin showed an LC50 of 5.44%w/v (r2 = 0.88). The toxicity of this extract was less than that of Imidacloprid which showed an LC50 of 0.0042% w/v (r2 = 0.99). The toxicity to non-target organisms was determined. This extract showed toxicity to guppies ((LC50 = 2.53 and 4.27 ppm for females and males, respectively; r2 = 0.97 and 0.97, respectively), bees (LC50 = 4.38% w/v, r2 = 0.95) and mice (no oral acute toxicity and no dermal inflammation but showed eye irritation in 1 day which became normal within 3 days). In vitro detoxification enzyme activities of carboxylesterase, acetylcholinesterase and glutathione-s-transferase from BPH after 24 hours exposure were also observed. Carboxylesterase showed stronger activity than other enzymes. Toxicity in terms of LC50 values of both the extract and imidacloprid treatments increased in each generation. The LC50 values for each generation were 4.22-6.67 after sequential spraying. After the ethanol extract was kept at 4 degrees C, room temperature and 55 degrees C for 3 months, the quantity of alpha-mangostin and the BPH control efficiency was lower at 55 degrees C than those for other temperatures. The results from this research indicate that mangosteen pericarp extract can be an alternative insecticide for the control of BPH, which may possess high efficiency, cause with fewer environmental problems and result in less resistance in the BPH.

Brown planthopper, Nilaparvata lugens Stal., (BPH) was the most devastating insect pest on rice in many partS of Asia. The Outbreak of BPH? which is resistant to many synthetic insecticides can cause total rice crop loss. This research was done to evaluate the efficiency of mangostin from the pericarp of mangosteen fruit extract (Garcina mangostana L.) as the alternative control of BPH. The pericarp of mangosteen fruit was extracted by Soxhlet apparatus using ethanol as a solvent and purified by chromatography method then qualified structure by 2D-NMR, MS and IR. The crude extracts contained mangostin ca. 2.956% w/w. This extract was trailed by the topical sprayer method with 1st, 2nd, 3rd, 4th and 5th nymph and adult BPH shows toxicity in term of LC50 ca. 1.39, 2.26, 5.44, 4.49, 4.03 and 3.84 % w/v at 24 h exposure, respectively. The in vitro enzyme activity from BPH survived after 24 h exposure and showed to inhibit the carboxylesterase (CarE), acetylchoinesterase (AchE) and glutathione-S-transferase (GST) activities which the correction factors of CarE, AchE and GST indicated ca. 1.21-2.05 fold, 1.24-2.50 fold and 1.01-3.34 fold, respectively. Moreover, the data shows that the carboxylesterase may play an important role to detoxify this extract. The results suggested that pericarp of mangosteen fruit extract which have mangostin as active ingredient compound shows mechanism as the inhibitor of detoxification enzymes. Thus, it is likely to be uses this extract as an insecticide alternative to the control of BPH.